Methods and compositions for diagnosis and prognosis of renal injury and renal failure

ABSTRACT

Disclosed are methods and compositions for monitoring, diagnosis, prognosis, and determination of treatment regimens in subjects suffering from or suspected of having a renal injury The methods use assays that detect one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, SIOO-AI2, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-I receptor antagonist, Interleukin-I beta, lnterleukun-10, lnterieukun-15, lnterieukun-3, Myeloperoxidase, Nidogen-I, soluble Oxidized low-density lipoprotein receptor I, Pappalysin-I, soluble P-selectin glycoprotein ligand I, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinasel, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule I, and Vascular endothelial growth factor A.

The present invention claims priority from U.S. Provisional Patent Application 61/115,044 filed Nov. 15, 2008; U.S. Provisional Patent Application 61/107,290 filed Oct. 21, 2008; U.S. Provisional Patent Application 61/113,102 filed Nov. 10, 2008; U.S. Provisional Patent Application 61/107,301 filed Oct. 21, 2008; U.S. Provisional Patent Application 61/115,047 filed Nov. 15, 2008; U.S. Provisional Patent Application 61/115,051 filed Nov. 15, 2008; U.S. Provisional Patent Application 61/113,045 filed Nov. 10, 2008; U.S. Provisional Patent Application 61/115,057 filed Nov. 15, 2008; U.S. Provisional Patent Application 61/117,167 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/117,157 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/117,146 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/107,281 filed Oct. 21, 2008; U.S. Provisional Patent Application 61/115,022 filed Nov. 14, 2008; U.S. Provisional Patent Application 61/117,154 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/117,152 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/115,019 filed Nov. 14, 2008; U.S. Provisional Patent Application 61/115,017 filed Nov. 14, 2008; U.S. Provisional Patent Application 61/113,021 filed Nov. 10, 2008; U.S. Provisional Patent Application 61/113,056 filed Nov. 10, 2008; U.S. Provisional Patent Application 61/107,297 filed Oct. 21, 2008; U.S. Provisional Patent Application 61/115,045 filed Nov. 15, 2008; U.S. Provisional Patent Application 61/107,304 filed Oct. 21, 2008; U.S. Provisional Patent Application 61/113,050 filed Nov. 10, 2008; U.S. Provisional Patent Application 61/115,048 filed Nov. 15, 2008; U.S. Provisional Patent Application 61/113,096 filed Nov. 10, 2008; U.S. Provisional Patent Application 61/117,140 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/117,172 filed Nov. 22, 2008; U.S. Provisional Patent Application 61/113,083 filed Nov. 10, 2008; and U.S. Provisional Patent Application 61/117,141 filed Nov. 22, 2008, each of which is hereby incorporated in its entirety including all tables, figures, and claims.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been submitted via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Nov. 19, 2009, is named AST18200PC_SeqListing.txt, and is 119 kilobytes in size.

BACKGROUND OF THE INVENTION

The following discussion of the background of the invention is merely provided to aid the reader in understanding the invention and is not admitted to describe or constitute prior art to the present invention.

The kidney is responsible for water and solute excretion from the body. Its functions include maintenance of acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure. As such, loss of kidney function through injury and/or disease results in substantial morbidity and mortality. A detailed discussion of renal injuries is provided in Harrison's Principles of Internal Medicine, 17^(th) Ed., McGraw Hill, New York, pages 1741-1830, which are hereby incorporated by reference in their entirety. Renal disease and/or injury may be acute or chronic. Acute and chronic kidney disease are described as follows (from Current Medical Diagnosis & Treatment 2008, 47^(th) Ed, McGraw Hill, New York, pages 785-815, which are hereby incorporated by reference in their entirety): “Acute renal failure is worsening of renal function over hours to days, resulting in the retention of nitrogenous wastes (such as urea nitrogen) and creatinine in the blood. Retention of these substances is called azotemia. Chronic renal failure (chronic kidney disease) results from an abnormal loss of renal function over months to years”.

Acute renal failure (ARF, also known as acute kidney injury, or AKI) is an abrupt (typically detected within about 48 hours to 1 week) reduction in glomerular filtration. This loss of filtration capacity results in retention of nitrogenous (urea and creatinine) and non-nitrogenous waste products that are normally excreted by the kidney, a reduction in urine output, or both. It is reported that ARF complicates about 5% of hospital admissions, 4-15% of cardiopulmonary bypass surgeries, and up to 30% of intensive care admissions. ARF may be categorized as prerenal, intrinsic renal, or postrenal in causation. Intrinsic renal disease can be further divided into glomerular, tubular, interstitial, and vascular abnormalities. Major causes of ARF are described in the following table, which is adapted from the Merck Manual, 17^(th) ed., Chapter 222, and which is hereby incorporated by reference in their entirety:

Type Risk Factors Prerenal ECF volume depletion Excessive diuresis, hemorrhage, GI losses, loss of intravascular fluid into the extravascular space (due to ascites, peritonitis, pancreatitis, or burns), loss of skin and mucus membranes, renal salt- and water-wasting states Low cardiac output Cardiomyopathy, MI, cardiac tamponade, pulmonary embolism, pulmonary hypertension, positive-pressure mechanical ventilation Low systemic vascular Septic shock, liver failure, antihypertensive drugs resistance Increased renal vascular NSAIDs, cyclosporines, tacrolimus, hypercalcemia, resistance anaphylaxis, anesthetics, renal artery obstruction, renal vein thrombosis, sepsis, hepatorenal syndrome Decreased efferent arteriolar ACE inhibitors or angiotensin II receptor blockers tone (leading to decreased GFR from reduced glomerular transcapillary pressure, especially in patients with bilateral renal artery stenosis) Intrinsic Renal Acute tubular injury Ischemia (prolonged or severe prerenal state): surgery, hemorrhage, arterial or venous obstruction; Toxins: NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, streptozotocin Acute glomerulonephritis ANCA-associated: Crescentic glomerulonephritis, polyarteritis nodosa, Wegener's granulomatosis; Anti-GBM glomerulonephritis: Goodpasture's syndrome; Immune- complex: Lupus glomerulonephritis, postinfectious glomerulonephritis, cryoglobulinemic glomerulonephritis Acute tubulointerstitial Drug reaction (eg, β-lactams, NSAIDs, sulfonamides, nephritis ciprofloxacin, thiazide diuretics, furosemide, phenytoin, allopurinol, pyelonephritis, papillary necrosis Acute vascular nephropathy Vasculitis, malignant hypertension, thrombotic microangiopathies, scleroderma, atheroembolism Infiltrative diseases Lymphoma, sarcoidosis, leukemia Postrenal Tubular precipitation Uric acid (tumor lysis), sulfonamides, triamterene, acyclovir, indinavir, methotrexate, ethylene glycol ingestion, myeloma protein, myoglobin Ureteral obstruction Intrinsic: Calculi, clots, sloughed renal tissue, fungus ball, edema, malignancy, congenital defects; Extrinsic: Malignancy, retroperitoneal fibrosis, ureteral trauma during surgery or high impact injury Bladder obstruction Mechanical: Benign prostatic hyperplasia, prostate cancer, bladder cancer, urethral strictures, phimosis, paraphimosis, urethral valves, obstructed indwelling urinary catheter; Neurogenic: Anticholinergic drugs, upper or lower motor neuron lesion

In the case of ischemic ARF, the course of the disease may be divided into four phases. During an initiation phase, which lasts hours to days, reduced perfusion of the kidney is evolving into injury. Glomerular ultrafiltration reduces, the flow of filtrate is reduced due to debris within the tubules, and back leakage of filtrate through injured epithelium occurs. Renal injury can be mediated during this phase by reperfusion of the kidney. Initiation is followed by an extension phase which is characterized by continued ischemic injury and inflammation and may involve endothelial damage and vascular congestion. During the maintenance phase, lasting from 1 to 2 weeks, renal cell injury occurs, and glomerular filtration and urine output reaches a minimum. A recovery phase can follow in which the renal epithelium is repaired and GFR gradually recovers. Despite this, the survival rate of subjects with ARF may be as low as about 60%.

Acute kidney injury caused by radiocontrast agents (also called contrast media) and other nephrotoxins such as cyclosporine, antibiotics including aminoglycosides and anticancer drugs such as cisplatin manifests over a period of days to about a week. Contrast induced nephropathy (CIN, which is AKI caused by radiocontrast agents) is thought to be caused by intrarenal vasoconstriction (leading to ischemic injury) and from the generation of reactive oxygen species that are directly toxic to renal tubular epithelial cells. CIN classically presents as an acute (onset within 24-48 h) but reversible (peak 3-5 days, resolution within 1 week) rise in blood urea nitrogen and serum creatinine.

A commonly reported criteria for defining and detecting AKI is an abrupt (typically within about 2-7 days or within a period of hospitalization) elevation of serum creatinine. Although the use of serum creatinine elevation to define and detect AKI is well established, the magnitude of the serum creatinine elevation and the time over which it is measured to define AKI varies considerably among publications. Traditionally, relatively large increases in serum creatinine such as 100%, 200%, an increase of at least 100% to a value over 2 mg/dL and other definitions were used to define AKI. However, the recent trend has been towards using smaller serum creatinine rises to define AKI. The relationship between serum creatinine rise, AKI and the associated health risks are reviewed in Praught and Shlipak, Curr Opin Nephrol Hypertens 14:265-270, 2005 and Chertow et al, J Am Soc Nephrol 16: 3365-3370, 2005, which, with the references listed therein, are hereby incorporated by reference in their entirety. As described in these publications, acute worsening renal function (AKI) and increased risk of death and other detrimental outcomes are now known to be associated with very small increases in serum creatinine. These increases may be determined as a relative (percent) value or a nominal value. Relative increases in serum creatinine as small as 20% from the pre-injury value have been reported to indicate acutely worsening renal function (AKI) and increased health risk, but the more commonly reported value to define AKI and increased health risk is a relative increase of at least 25%. Nominal increases as small as 0.3 mg/dL, 0.2 mg/dL or even 0.1 mg/dL have been reported to indicate worsening renal function and increased risk of death. Various time periods for the serum creatinine to rise to these threshold values have been used to define AKI, for example, ranging from 2 days, 3 days, 7 days, or a variable period defined as the time the patient is in the hospital or intensive care unit. These studies indicate there is not a particular threshold serum creatinine rise (or time period for the rise) for worsening renal function or AKI, but rather a continuous increase in risk with increasing magnitude of serum creatinine rise.

One study (Lassnigg et all, J Am Soc Nephrol 15:1597-1605, 2004, hereby incorporated by reference in its entirety) investigated both increases and decreases in serum creatinine. Patients with a mild fall in serum creatinine of −0.1 to −0.3 mg/dL following heart surgery had the lowest mortality rate. Patients with a larger fall in serum creatinine (more than or equal to −0.4 mg/dL) or any increase in serum creatinine had a larger mortality rate. These findings caused the authors to conclude that even very subtle changes in renal function (as detected by small creatinine changes within 48 hours of surgery) seriously effect patient's outcomes. In an effort to reach consensus on a unified classification system for using serum creatinine to define AKI in clinical trials and in clinical practice, Bellomo et al., Crit Care. 8(4):R204-12, 2004, which is hereby incorporated by reference in its entirety, proposes the following classifications for stratifying AKI patients:

“Risk”: serum creatinine increased 1.5 fold from baseline OR urine production of <0.5 ml/kg body weight/hr for 6 hours;

“Injury”: serum creatinine increased 2.0 fold from baseline OR urine production <0.5 ml/kg/hr for 12 h;

“Failure”: serum creatinine increased 3.0 fold from baseline OR creatinine >355 μmol/l (with a rise of >44) or urine output below 0.3 ml/kg/hr for 24 h or anuria for at least 12 hours;

And included two clinical outcomes:

“Loss”: persistent need for renal replacement therapy for more than four weeks.

“ESRD”: end stage renal disease—the need for dialysis for more than 3 months.

These criteria are called the RIFLE criteria, which provide a useful clinical tool to classify renal status. As discussed in Kellum, Crit. Care Med. 36: S141-45, 2008 and Ricci et al., Kidney Int. 73, 538-546, 2008, each hereby incorporated by reference in its entirety, the RIFLE criteria provide a uniform definition of AKI which has been validated in numerous studies.

More recently, Mehta et al., Crit. Care 11:R31 (doi:10.1186.cc5713), 2007, hereby incorporated by reference in its entirety, proposes the following similar classifications for stratifying AKI patients, which have been modified from RIFLE:

“Stage I”: increase in serum creatinine of more than or equal to 0.3 mg/dL (≥26.4 μmol/L) or increase to more than or equal to 150% (1.5-fold) from baseline OR urine output less than 0.5 mL/kg per hour for more than 6 hours;

“Stage II”: increase in serum creatinine to more than 200% (>2-fold) from baseline OR urine output less than 0.5 mL/kg per hour for more than 12 hours;

“Stage III”: increase in serum creatinine to more than 300% (>3-fold) from baseline OR serum creatinine ≥354 μmol/L accompanied by an acute increase of at least 44 μmol/L OR urine output less than 0.3 mL/kg per hour for 24 hours or anuria for 12 hours.

The CIN Consensus Working Panel (McCollough et al, Rev Cardiovasc Med. 2006; 7(4): 177-197, hereby incorporated by reference in its entirety) uses a serum creatinine rise of 25% to define Contrast induced nephropathy (which is a type of AKI). Although various groups propose slightly different criteria for using serum creatinine to detect AKI, the consensus is that small changes in serum creatinine, such as 0.3 mg/dL or 25%, are sufficient to detect AKI (worsening renal function) and that the magnitude of the serum creatinine change is an indicator of the severity of the AKI and mortality risk.

Although serial measurement of serum creatinine over a period of days is an accepted method of detecting and diagnosing AKI and is considered one of the most important tools to evaluate AKI patients, serum creatinine is generally regarded to have several limitations in the diagnosis, assessment and monitoring of AKI patients. The time period for serum creatinine to rise to values (e.g., a 0.3 mg/dL or 25% rise) considered diagnostic for AKI can be 48 hours or longer depending on the definition used. Since cellular injury in AKI can occur over a period of hours, serum creatinine elevations detected at 48 hours or longer can be a late indicator of injury, and relying on serum creatinine can thus delay diagnosis of AKI. Furthermore, serum creatinine is not a good indicator of the exact kidney status and treatment needs during the most acute phases of AKI when kidney function is changing rapidly. Some patients with AKI will recover fully, some will need dialysis (either short term or long term) and some will have other detrimental outcomes including death, major adverse cardiac events and chronic kidney disease. Because serum creatinine is a marker of filtration rate, it does not differentiate between the causes of AKI (pre-renal, intrinsic renal, post-renal obstruction, atheroembolic, etc) or the category or location of injury in intrinsic renal disease (for example, tubular, glomerular or interstitial in origin). Urine output is similarly limited, Knowing these things can be of vital importance in managing and treating patients with AKI.

These limitations underscore the need for better methods to detect and assess AKI, particularly in the early and subclinical stages, but also in later stages when recovery and repair of the kidney can occur. Furthermore, there is a need to better identify patients who are at risk of having an AKI.

BRIEF SUMMARY OF THE INVENTION

It is an object of the invention to provide methods and compositions for evaluating renal function in a subject. As described herein, measurement of one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, S100-A12, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-1 receptor antagonist, Interleukin-1 beta, Interleukin-10, Interleukin-15, Interleukin-3, Myeloperoxidase, Nidogen-1, soluble Oxidized low-density lipoprotein receptor 1, Pappalysin-1, soluble P-selectin glycoprotein ligand 1, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinase 1, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule 1, and Vascular endothelial growth factor A (collectively referred to herein as “kidney injury markers, and individually as a “kidney injury marker”) can be used for diagnosis, prognosis, risk stratification, staging, monitoring, categorizing and determination of further diagnosis and treatment regimens in subjects suffering or at risk of suffering from an injury to renal function, reduced renal function, and/or acute renal failure (also called acute kidney injury).

These kidney injury markers may be used, individually or in panels comprising a plurality of kidney injury markers, for risk stratification (that is, to identify subjects at risk for a future injury to renal function, for future progression to reduced renal function, for future progression to ARF, for future improvement in renal function, etc.); for diagnosis of existing disease (that is, to identify subjects who have suffered an injury to renal function, who have progressed to reduced renal function, who have progressed to ARF, etc.); for monitoring for deterioration or improvement of renal function; and for predicting a future medical outcome, such as improved or worsening renal function, a decreased or increased mortality risk, a decreased or increased risk that a subject will require renal replacement therapy (i.e., hemodialysis, peritoneal dialysis, hemofiltration, and/or renal transplantation, a decreased or increased risk that a subject will recover from an injury to renal function, a decreased or increased risk that a subject will recover from ARF, a decreased or increased risk that a subject will progress to end stage renal disease, a decreased or increased risk that a subject will progress to chronic renal failure, a decreased or increased risk that a subject will suffer rejection of a transplanted kidney, etc.

In a first aspect, the present invention relates to methods for evaluating renal status in a subject. These methods comprise performing an assay method that is configured to detect one or more kidney injury markers of the present invention in a body fluid sample obtained from the subject. The assay result(s), for example a measured concentration of one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, S100-A12, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-1 receptor antagonist, Interleukin-1 beta, Interleukin-10, Interleukin-15, Interleukin-3, Myeloperoxidase, Nidogen-1, soluble Oxidized low-density lipoprotein receptor 1, Pappalysin-1, soluble P-selectin glycoprotein ligand 1, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinase 1, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule 1, and Vascular endothelial growth factor A is/are then correlated to the renal status of the subject. This correlation to renal status may include correlating the assay result(s) to one or more of risk stratification, diagnosis, prognosis, staging, classifying and monitoring of the subject as described herein. Thus, the present invention utilizes one or more kidney injury markers of the present invention for the evaluation of renal injury.

In certain embodiments, the methods for evaluating renal status described herein are methods for risk stratification of the subject; that is, assigning a likelihood of one or more future changes in renal status to the subject. In these embodiments, the assay result(s) is/are correlated to one or more such future changes. The following are preferred risk stratification embodiments.

In preferred risk stratification embodiments, these methods comprise determining a subject's risk for a future injury to renal function, and the assay result(s) is/are correlated to a likelihood of such a future injury to renal function. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of suffering a future injury to renal function is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of suffering a future injury to renal function is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold.

In other preferred risk stratification embodiments, these methods comprise determining a subject's risk for future reduced renal function, and the assay result(s) is/are correlated to a likelihood of such reduced renal function. For example, the measured concentrations may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of suffering a future reduced renal function is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of future reduced renal function is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold.

In still other preferred risk stratification embodiments, these methods comprise determining a subject's likelihood for a future improvement in renal function, and the assay result(s) is/are correlated to a likelihood of such a future improvement in renal function. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of a future improvement in renal function is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold. For a “negative going” kidney injury marker, an increased likelihood of a future improvement in renal function is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold.

In yet other preferred risk stratification embodiments, these methods comprise determining a subject's risk for progression to ARF, and the result(s) is/are correlated to a likelihood of such progression to ARF. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of progression to ARF is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of progression to ARF is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold.

And in other preferred risk stratification embodiments, these methods comprise determining a subject's outcome risk, and the assay result(s) is/are correlated to a likelihood of the occurrence of a clinical outcome related to a renal injury suffered by the subject. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of one or more of: acute kidney injury, progression to a worsening stage of AKI, mortality, a requirement for renal replacement therapy, a requirement for withdrawal of renal toxins, end stage renal disease, heart failure, stroke, myocardial infarction, progression to chronic kidney disease, etc., is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of one or more of: acute kidney injury, progression to a worsening stage of AKI, mortality, a requirement for renal replacement therapy, a requirement for withdrawal of renal toxins, end stage renal disease, heart failure, stroke, myocardial infarction, progression to chronic kidney disease, etc., is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold.

In such risk stratification embodiments, preferably the likelihood or risk assigned is that an event of interest is more or less likely to occur within 180 days of the time at which the body fluid sample is obtained from the subject. In particularly preferred embodiments, the likelihood or risk assigned relates to an event of interest occurring within a shorter time period such as 18 months, 120 days, 90 days, 60 days, 45 days, 30 days, 21 days, 14 days, 7 days, 5 days, 96 hours, 72 hours, 48 hours, 36 hours, 24 hours, 12 hours, or less. A risk at 0 hours of the time at which the body fluid sample is obtained from the subject is equivalent to diagnosis of a current condition.

In preferred risk stratification embodiments, the subject is selected for risk stratification based on the pre-existence in the subject of one or more known risk factors for prerenal, intrinsic renal, or postrenal ARF. For example, a subject undergoing or having undergone major vascular surgery, coronary artery bypass, or other cardiac surgery; a subject having pre-existing congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, proteinuria, renal insufficiency, glomerular filtration below the normal range, cirrhosis, serum creatinine above the normal range, or sepsis; or a subject exposed to NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, or streptozotocin are all preferred subjects for monitoring risks according to the methods described herein. This list is not meant to be limiting. By “pre-existence” in this context is meant that the risk factor exists at the time the body fluid sample is obtained from the subject. In particularly preferred embodiments, a subject is chosen for risk stratification based on an existing diagnosis of injury to renal function, reduced renal function, or ARF.

In other embodiments, the methods for evaluating renal status described herein are methods for diagnosing a renal injury in the subject; that is, assessing whether or not a subject has suffered from an injury to renal function, reduced renal function, or ARF. In these embodiments, the assay result(s), for example a measured concentration of one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, S100-A12, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-1 receptor antagonist, Interleukin-1 beta, Interleukin-10, Interleukin-15, Interleukin-3, Myeloperoxidase, Nidogen-1, soluble Oxidized low-density lipoprotein receptor 1, Pappalysin-1, soluble P-selectin glycoprotein ligand 1, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinase 1, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule 1, and Vascular endothelial growth factor A is/are correlated to the occurrence or nonoccurrence of a change in renal status. The following are preferred diagnostic embodiments.

In preferred diagnostic embodiments, these methods comprise diagnosing the occurrence or nonoccurrence of an injury to renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of such an injury. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury to renal function is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury to renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury to renal function is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury to renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold).

In other preferred diagnostic embodiments, these methods comprise diagnosing the occurrence or nonoccurrence of reduced renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of an injury causing reduced renal function. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury causing reduced renal function is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury causing reduced renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury causing reduced renal function is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury causing reduced renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold).

In yet other preferred diagnostic embodiments, these methods comprise diagnosing the occurrence or nonoccurrence of ARF, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of an injury causing ARF. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of ARF is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of ARF may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of ARF is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of ARF may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold).

In still other preferred diagnostic embodiments, these methods comprise diagnosing a subject as being in need of renal replacement therapy, and the assay result(s) is/are correlated to a need for renal replacement therapy. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury creating a need for renal replacement therapy is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal replacement therapy may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury creating a need for renal replacement therapy is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal replacement therapy may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold).

In still other preferred diagnostic embodiments, these methods comprise diagnosing a subject as being in need of renal transplantation, and the assay result (s0 is/are correlated to a need for renal transplantation. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury creating a need for renal transplantation is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal transplantation may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury creating a need for renal transplantation is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal transplantation may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold).

In still other embodiments, the methods for evaluating renal status described herein are methods for monitoring a renal injury in the subject; that is, assessing whether or not renal function is improving or worsening in a subject who has suffered from an injury to renal function, reduced renal function, or ARF. In these embodiments, the assay result(s), for example a measured concentration of one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, S100-A12, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-1 receptor antagonist, Interleukin-1 beta, Interleukin-10, Interleukin-15, Interleukin-3, Myeloperoxidase, Nidogen-1, soluble Oxidized low-density lipoprotein receptor 1, Pappalysin-1, soluble P-selectin glycoprotein ligand 1, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinase 1, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule 1, and Vascular endothelial growth factor A is/are correlated to the occurrence or nonoccurrence of a change in renal status. The following are preferred monitoring embodiments.

In preferred monitoring embodiments, these methods comprise monitoring renal status in a subject suffering from an injury to renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject.

In other preferred monitoring embodiments, these methods comprise monitoring renal status in a subject suffering from reduced renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject.

In yet other preferred monitoring embodiments, these methods comprise monitoring renal status in a subject suffering from acute renal failure, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject.

In other additional preferred monitoring embodiments, these methods comprise monitoring renal status in a subject at risk of an injury to renal function due to the pre-existence of one or more known risk factors for prerenal, intrinsic renal, or postrenal ARF, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject.

In still other embodiments, the methods for evaluating renal status described herein are methods for classifying a renal injury in the subject; that is, determining whether a renal injury in a subject is prerenal, intrinsic renal, or postrenal; and/or further subdividing these classes into subclasses such as acute tubular injury, acute glomerulonephritis acute tubulointerstitial nephritis, acute vascular nephropathy, or infiltrative disease; and/or assigning a likelihood that a subject will progress to a particular RIFLE stage. In these embodiments, the assay result(s), for example a measured concentration of one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, S100-A12, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-1 receptor antagonist, Interleukin-1 beta, Interleukin-10, Interleukin-15, Interleukin-3, Myeloperoxidase, Nidogen-1, soluble Oxidized low-density lipoprotein receptor 1, Pappalysin-1, soluble P-selectin glycoprotein ligand 1, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinase 1, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule 1, and Vascular endothelial growth factor A is/are correlated to a particular class and/or subclass. The following are preferred classification embodiments.

In preferred classification embodiments, these methods comprise determining whether a renal injury in a subject is prerenal, intrinsic renal, or postrenal; and/or further subdividing these classes into subclasses such as acute tubular injury, acute glomerulonephritis acute tubulointerstitial nephritis, acute vascular nephropathy, or infiltrative disease; and/or assigning a likelihood that a subject will progress to a particular RIFLE stage, and the assay result(s) is/are correlated to the injury classification for the subject. For example, the measured concentration may be compared to a threshold value, and when the measured concentration is above the threshold, a particular classification is assigned; alternatively, when the measured concentration is below the threshold, a different classification may be assigned to the subject.

A variety of methods may be used by the skilled artisan to arrive at a desired threshold value for use in these methods. For example, the threshold value may be determined from a population of normal subjects by selecting a concentration representing the 75^(th), 85^(th), 90^(th), 95^(th), or 99^(th) percentile of a kidney injury marker measured in such normal subjects. Alternatively, the threshold value may be determined from a “diseased” population of subjects, e.g., those suffering from an injury or having a predisposition for an injury (e.g., progression to ARF or some other clinical outcome such as death, dialysis, renal transplantation, etc.), by selecting a concentration representing the 75^(th), 85^(th), 90^(th), 95^(th), or 99^(th) percentile of a kidney injury marker measured in such subjects. In another alternative, the threshold value may be determined from a prior measurement of a kidney injury marker in the same subject; that is, a temporal change in the level of a kidney injury marker in the subject may be used to assign risk to the subject.

The foregoing discussion is not meant to imply, however, that the kidney injury markers of the present invention must be compared to corresponding individual thresholds. Methods for combining assay results can comprise the use of multivariate logistical regression, loglinear modeling, neural network analysis, n-of-m analysis, decision tree analysis, calculating ratios of markers, etc. This list is not meant to be limiting. In these methods, a composite result which is determined by combining individual markers may be treated as if it is itself a marker; that is, a threshold may be determined for the composite result as described herein for individual markers, and the composite result for an individual patient compared to this threshold.

The ability of a particular test to distinguish two populations can be established using ROC analysis. For example, ROC curves established from a “first” subpopulation which is predisposed to one or more future changes in renal status, and a “second” subpopulation which is not so predisposed can be used to calculate a ROC curve, and the area under the curve provides a measure of the quality of the test. Preferably, the tests described herein provide a ROC curve area greater than 0.5, preferably at least 0.6, more preferably 0.7, still more preferably at least 0.8, even more preferably at least 0.9, and most preferably at least 0.95.

In certain aspects, the measured concentration of one or more kidney injury markers, or a composite of such markers, may be treated as continuous variables. For example, any particular concentration can be converted into a corresponding probability of a future reduction in renal function for the subject, the occurrence of an injury, a classification, etc. In yet another alternative, a threshold that can provide an acceptable level of specificity and sensitivity in separating a population of subjects into “bins” such as a “first” subpopulation (e.g., which is predisposed to one or more future changes in renal status, the occurrence of an injury, a classification, etc.) and a “second” subpopulation which is not so predisposed. A threshold value is selected to separate this first and second population by one or more of the following measures of test accuracy:

an odds ratio greater than 1, preferably at least about 2 or more or about 0.5 or less, more preferably at least about 3 or more or about 0.33 or less, still more preferably at least about 4 or more or about 0.25 or less, even more preferably at least about 5 or more or about 0.2 or less, and most preferably at least about 10 or more or about 0.1 or less; a specificity of greater than 0.5, preferably at least about 0.6, more preferably at least about 0.7, still more preferably at least about 0.8, even more preferably at least about 0.9 and most preferably at least about 0.95, with a corresponding sensitivity greater than 0.2, preferably greater than about 0.3, more preferably greater than about 0.4, still more preferably at least about 0.5, even more preferably about 0.6, yet more preferably greater than about 0.7, still more preferably greater than about 0.8, more preferably greater than about 0.9, and most preferably greater than about 0.95; a sensitivity of greater than 0.5, preferably at least about 0.6, more preferably at least about 0.7, still more preferably at least about 0.8, even more preferably at least about 0.9 and most preferably at least about 0.95, with a corresponding specificity greater than 0.2, preferably greater than about 0.3, more preferably greater than about 0.4, still more preferably at least about 0.5, even more preferably about 0.6, yet more preferably greater than about 0.7, still more preferably greater than about 0.8, more preferably greater than about 0.9, and most preferably greater than about 0.95; at least about 75% sensitivity, combined with at least about 75% specificity; a positive likelihood ratio (calculated as sensitivity/(1-specificity)) of greater than 1, at least about 2, more preferably at least about 3, still more preferably at least about 5, and most preferably at least about 10; or a negative likelihood ratio (calculated as (1-sensitivity)/specificity) of less than 1, less than or equal to about 0.5, more preferably less than or equal to about 0.3, and most preferably less than or equal to about 0.1. The term “about” in the context of any of the above measurements refers to +/−5% of a given measurement.

Multiple thresholds may also be used to assess renal status in a subject. For example, a “first” subpopulation which is predisposed to one or more future changes in renal status, the occurrence of an injury, a classification, etc., and a “second” subpopulation which is not so predisposed can be combined into a single group. This group is then subdivided into three or more equal parts (known as tertiles, quartiles, quintiles, etc., depending on the number of subdivisions). An odds ratio is assigned to subjects based on which subdivision they fall into. If one considers a tertile, the lowest or highest tertile can be used as a reference for comparison of the other subdivisions. This reference subdivision is assigned an odds ratio of 1. The second tertile is assigned an odds ratio that is relative to that first tertile. That is, someone in the second tertile might be 3 times more likely to suffer one or more future changes in renal status in comparison to someone in the first tertile. The third tertile is also assigned an odds ratio that is relative to that first tertile.

In certain embodiments, the assay method is an immunoassay. Antibodies for use in such assays will specifically bind a full length kidney injury marker of interest, and may also bind one or more polypeptides that are “related” thereto, as that term is defined hereinafter. Numerous immunoassay formats are known to those of skill in the art. Preferred body fluid samples are selected from the group consisting of urine, blood, serum, saliva, tears, and plasma.

The foregoing method steps should not be interpreted to mean that the kidney injury marker assay result(s) is/are used in isolation in the methods described herein. Rather, additional variables or other clinical indicia may be included in the methods described herein. For example, a risk stratification, diagnostic, classification, monitoring, etc. method may combine the assay result(s) with one or more variables measured for the subject selected from the group consisting of demographic information (e.g., weight, sex, age, race), medical history (e.g., family history, type of surgery, pre-existing disease such as aneurism, congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, proteinuria, renal insufficiency, or sepsis, type of toxin exposure such as NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, or streptozotocin), clinical variables (e.g., blood pressure, temperature, respiration rate), risk scores (APACHE score, PREDICT score, TIMI Risk Score for UA/NSTEMI, Framingham Risk Score), a glomerular filtration rate, an estimated glomerular filtration rate, a urine production rate, a serum or plasma creatinine concentration, a urine creatinine concentration, a fractional excretion of sodium, a urine sodium concentration, a urine creatinine to serum or plasma creatinine ratio, a urine specific gravity, a urine osmolality, a urine urea nitrogen to plasma urea nitrogen ratio, a plasma BUN to creatinine ratio, a renal failure index calculated as urine sodium/(urine creatinine/plasma creatinine), a serum or plasma neutrophil gelatinase (NGAL) concentration, a urine NGAL concentration, a serum or plasma cystatin C concentration, a serum or plasma cardiac troponin concentration, a serum or plasma BNP concentration, a serum or plasma NTproBNP concentration, and a serum or plasma proBNP concentration. Other measures of renal function which may be combined with one or more kidney injury marker assay result(s) are described hereinafter and in Harrison's Principles of Internal Medicine, 17^(th) Ed., McGraw Hill, New York, pages 1741-1830, and Current Medical Diagnosis & Treatment 2008, 47^(th) Ed, McGraw Hill, New York, pages 785-815, each of which are hereby incorporated by reference in their entirety.

When more than one marker is measured, the individual markers may be measured in samples obtained at the same time, or may be determined from samples obtained at different (e.g., an earlier or later) times. The individual markers may also be measured on the same or different body fluid samples. For example, one kidney injury marker may be measured in a serum or plasma sample and another kidney injury marker may be measured in a urine sample. In addition, assignment of a likelihood may combine an individual kidney injury marker assay result with temporal changes in one or more additional variables.

In various related aspects, the present invention also relates to devices and kits for performing the methods described herein. Suitable kits comprise reagents sufficient for performing an assay for at least one of the described kidney injury markers, together with instructions for performing the described threshold comparisons.

In certain embodiments, reagents for performing such assays are provided in an assay device, and such assay devices may be included in such a kit. Preferred reagents can comprise one or more solid phase antibodies, the solid phase antibody comprising antibody that detects the intended biomarker target(s) bound to a solid support. In the case of sandwich immunoassays, such reagents can also include one or more detectably labeled antibodies, the detectably labeled antibody comprising antibody that detects the intended biomarker target(s) bound to a detectable label. Additional optional elements that may be provided as part of an assay device are described hereinafter.

Detectable labels may include molecules that are themselves detectable (e.g., fluorescent moieties, electrochemical labels, ecl (electrochemical luminescence) labels, metal chelates, colloidal metal particles, etc.) as well as molecules that may be indirectly detected by production of a detectable reaction product (e.g., enzymes such as horseradish peroxidase, alkaline phosphatase, etc.) or through the use of a specific binding molecule which itself may be detectable (e.g., a labeled antibody that binds to the second antibody, biotin, digoxigenin, maltose, oligohistidine, 2,4-dintrobenzene, phenylarsenate, ssDNA, dsDNA, etc.).

Generation of a signal from the signal development element can be performed using various optical, acoustical, and electrochemical methods well known in the art. Examples of detection modes include fluorescence, radiochemical detection, reflectance, absorbance, amperometry, conductance, impedance, interferometry, ellipsometry, etc. In certain of these methods, the solid phase antibody is coupled to a transducer (e.g., a diffraction grating, electrochemical sensor, etc) for generation of a signal, while in others, a signal is generated by a transducer that is spatially separate from the solid phase antibody (e.g., a fluorometer that employs an excitation light source and an optical detector). This list is not meant to be limiting. Antibody-based biosensors may also be employed to determine the presence or amount of analytes that optionally eliminate the need for a labeled molecule.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 provides data tables determined in accordance with Example 6 for the comparison of marker levels in urine samples collected for Cohort 1 (patients that did not progress beyond RIFLE stage 0) and in urine samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage R, I or F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 2 provides data tables determined in accordance with Example 7 for the comparison of marker levels in urine samples collected for Cohort 1 (patients that did not progress beyond RIFLE stage 0 or R) and in urine samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage I or F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 3 provides data tables determined in accordance with Example 8 for the comparison of marker levels in urine samples collected for Cohort 1 (patients that reached, but did not progress beyond, RIFLE stage R) and in urine samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage I or F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 4 provides data tables determined in accordance with Example 9 for the comparison of marker levels in urine samples collected for Cohort 1 (patients that did not progress beyond RIFLE stage 0) and in urine samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 5 provides data tables determined in accordance with Example 6 for the comparison of marker levels in plasma samples collected for Cohort 1 (patients that did not progress beyond RIFLE stage 0) and in plasma samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage R, I or F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 6 provides data tables determined in accordance with Example 7 for the comparison of marker levels in plasma samples collected for Cohort 1 (patients that did not progress beyond RIFLE stage 0 or R) and in plasma samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage I or F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 7 provides data tables determined in accordance with Example 8 for the comparison of marker levels in plasma samples collected for Cohort 1 (patients that reached, but did not progress beyond, RIFLE stage R) and in plasma samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage I or F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

FIG. 8 provides data tables determined in accordance with Example 9 for the comparison of marker levels in plasma samples collected for Cohort 1 (patients that did not progress beyond RIFLE stage 0) and in plasma samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage F in Cohort 2. Tables provide descriptive statistics, AUC analysis, and sensitivity, specificity and odds ratio calculations at various threshold (cutoff) levels for the various markers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods and compositions for diagnosis, differential diagnosis, risk stratification, monitoring, classifying and determination of treatment regimens in subjects suffering or at risk of suffering from injury to renal function, reduced renal function and/or acute renal failure through measurement of one or more kidney injury markers. In various embodiments, a measured concentration of one or more markers selected from the group consisting of Cytoplasmic aspartate aminotransferase, soluble Tumor necrosis factor receptor superfamily member 5, soluble CD40 Ligand, soluble C-X-C Motif chemokine 16, S100-A12, Eotaxin, soluble E-selectin, Fibronectin, Granulocyte colony-stimulating factor, Granulocyte-macrophage colony-stimulating factor, Heparin-binding growth factor 2, soluble Hepatocyte growth factor receptor, Interleukin-1 receptor antagonist, Interleukin-1 beta, Interleukin-10, Interleukin-15, Interleukin-3, Myeloperoxidase, Nidogen-1, soluble Oxidized low-density lipoprotein receptor 1, Pappalysin-1, soluble P-selectin glycoprotein ligand 1, Antileukoproteinase, soluble Kit ligand, Tissue inhibitor of metalloproteinase 1, Tissue inhibitor of metalloproteinase 2, soluble Tumor necrosis factor, soluble Vascular cell adhesion molecule 1, and Vascular endothelial growth factor A, or one or more markers related thereto, are correlated to the renal status of the subject.

For purposes of this document, the following definitions apply:

As used herein, an “injury to renal function” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) measurable reduction in a measure of renal function. Such an injury may be identified, for example, by a decrease in glomerular filtration rate or estimated GFR, a reduction in urine output, an increase in serum creatinine, an increase in serum cystatin C, a requirement for renal replacement therapy, etc. “Improvement in Renal Function” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) measurable increase in a measure of renal function. Preferred methods for measuring and/or estimating GFR are described hereinafter. As used herein, “reduced renal function” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) reduction in kidney function identified by an absolute increase in serum creatinine of greater than or equal to 0.1 mg/dL (≥8.8 μmol/L), a percentage increase in serum creatinine of greater than or equal to 20% (1.2-fold from baseline), or a reduction in urine output (documented oliguria of less than 0.5 ml/kg per hour). As used herein, “acute renal failure” or “ARF” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) reduction in kidney function identified by an absolute increase in serum creatinine of greater than or equal to 0.3 mg/dl (≥26.4 μmol/l), a percentage increase in serum creatinine of greater than or equal to 50% (1.5-fold from baseline), or a reduction in urine output (documented oliguria of less than 0.5 ml/kg per hour for at least 6 hours). This term is synonymous with “acute kidney injury” or “AKI.”

In this regard, the skilled artisan will understand that the signals obtained from an immunoassay are a direct result of complexes formed between one or more antibodies and the target biomolecule (i.e., the analyte) and polypeptides containing the necessary epitope(s) to which the antibodies bind. While such assays may detect the full length biomarker and the assay result be expressed as a concentration of a biomarker of interest, the signal from the assay is actually a result of all such “immunoreactive” polypeptides present in the sample. Expression of biomarkers may also be determined by means other than immunoassays, including protein measurements (such as dot blots, western blots, chromatographic methods, mass spectrometry, etc.) and nucleic acid measurements (mRNA quatitation). This list is not meant to be limiting.

As used herein, the term “Cytoplasmic aspartate aminotransferase” refers to one or more polypeptides present in a biological sample that are derived from the Cytoplasmic aspartate aminotransferase precursor (Swiss-Prot P17174 (SEQ ID NO: 1)).

        10         20         30         40 MAPPSVFAEV PQAQPVLVFK LTADFREDPD PRKVNLGVGA         50         60         70         80 YRTDDCHPWV LPVVKKVEQK IANDNSLNHE YLPILGLAEF         90        100        110        120 RSCASRLALG DDSPALKEKR VGGVQSLGGT GALRIGADFL        130        140        150        160 ARWYNGTNNK NTPVYVSSPT WENHNAVFSA AGFKDIRSYR        170        180        190        200 YWDAEKRGLD LQGFLNDLEN APEFSIVVLH ACAHNPTGID        210        220        230        240 PTPEQWKQIA SVMKHRFLFP FFDSAYQGFA SGNLERDAWA        250        260        270        280 IRYFVSEGFE FFCAQSFSKN FGLYNERVGN LTVVGKEPES        290        300        310        320 ILQVLSQMEK IVRITWSNPP AQGARIVAST LSNPELFEEW        330        340        350        360 TGNVKTMADR ILTMRSELRA RLEALKTPGT WNHITDQIGM        370        380        390        400 FSFTGLNPKQ VEYLVNEKHI YLLPSGRINV SGLTTKNLDY        410 VATSIHEAVT KIQ

The following domains have been identified in Cytoplasmic aspartate aminotransferase:

Residues Length Domain ID 1 1 Initiator methionine 2-413 412 Cytoplasmic aspartate aminotransferase

As used herein, the term “tumor necrosis factor receptor superfamily member 5” refers to one or more polypeptides present in a biological sample that are derived from the tumor necrosis factor receptor superfamily member 5 precursor (Swiss-Prot P25942 (SEQ ID NO: 2)).

        10         20         30         40 MVRLPLQCVL WGCLLTAVHP EPPTACREKQ YLINSQCCSL         50         60         70         80 CQPGQKLVSD CTEFTETECL PCGESEFLDT WNRETHCHQH         90        100        110        120 KYCDPNLGLR VQQKGTSETD TICTCEEGWH CTSEACESCV        130        140        150        160 LHRSCSPGFG VKQIATGVSD TICEPCPVGF FSNVSSAFEK        170        180        190        200 CHPWTSCETK DLVVQQAGTN KTDVVCGPQD RLRALVVIPI        210        220        230        240 IFGILFAILL VLVFIKKVAK KPTNKAPHPK QEPQEINFPD        250        260        270 DLPGSNTAAP VQETLHGCQP VTQEDGKESR ISVQERQ

Most preferably, the tumor necrosis factor receptor superfamily member 5 assay detects one or more soluble forms of tumor necrosis factor receptor superfamily member 5. Tumor necrosis factor receptor superfamily member 5 is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of tumor necrosis factor receptor superfamily member 5 generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in tumor necrosis factor receptor superfamily member 5:

Residues Length Domain ID 1-20 20 signal sequence 21-277 257 tumor necrosis factor receptor superfamily member 5 21-193 173 extracellular 194-215  22 transmembrane 216-277  62 cytoplasmic

In addition, 1 alternative splice form of tumor necrosis factor receptor superfamily member 5 is known. This form is considered a tumor necrosis factor receptor superfamily member 5 for purposes of the present invention, and soluble forms of this alternative splice form is considered a soluble tumor necrosis factor receptor superfamily member 5 for purposes of the present invention.

As used herein, the term “CD40 ligand” refers to one or more polypeptides present in a biological sample that are derived from the CD40 ligand precursor (Swiss-Prot P29965 (SEQ ID NO: 3)).

        10         20         30         40 MIETYNQTSP RSAATGLPIS MKIFMYLLTV FLITQMIGSA         50         60         70         80 LFAVYLHRRL DKIEDERNLH EDFVFMKTIQ RCNTGERSLS         90        100        110        120 LLNCEEIKSQ FEGFVKDIML NKEETKKENS FEMQKGDQNP        130        140        150        160 QIAAHVISEA SSKTTSVLQW AEKGYYTMSN NLVTLENGKQ        170        180        190        200 LTVKRQGLYY IYAQVTFCSN REASSQAPFI ASLCLKSPGR        210        220        230        240 FERILLRAAN THSSAKPCGQ QSIHLGGVFE LQPGASVFVN        250        260 VTDPSQVSHG TGFTSFGLLK L

Most preferably, the CD40 ligand assay detects one or more soluble forms of CD40 ligand. CD40 ligand is a single-pass type II membrane protein having a large extracellular domain, most or all of which is present in soluble forms of CD40 ligand generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in CD40 ligand:

Residues Length Domain ID  1-261 261 CD40 ligand, membrane bound form 113-261 149 CD40 ligand, soluble form  47-261 215 extracellular 23-46 24 anchor signal  1-22 22 cytoplasmic 112-113 2 cleavage site

As used herein, the term “C-X-C motif chemokine 16” refers to one or more polypeptides present in a biological sample that are derived from the C-X-C motif chemokine 16 precursor (Swiss-Prot Q9H2A7 (SEQ ID NO: 4)).

        10         20         30         40 MGRDLRPGSR VLLLLLLLLL VYLTQPGNGN EGSVTGSCYC         50         60         70         80 GKRISSDSPP SVQFMNRLRK HLRAYHRCLY YTRFQLLSWS         90        100        110        120 VCGGNKDPWV QELMSCLDLK ECGHAYSGIV AHQKHLLPTS        130        140        150        160 PPISQASEGA SSDIHTPAQM LLSTLQSTQR PTLPVGSLSS        170        180        190        200 DKELTRPNET TIHTAGHSLA AGPEAGENQK QPEKNAGPTA        210        220        230        240 RTSATVPVLC LLAIIFILTA ALSYVLCKRR RGQSPQSSPD        250 LPVHYIPVAP DSNT

Most preferably, the C-X-C motif chemokine 16 assay detects one or more soluble forms of C-X-C motif chemokine 16. C-X-C motif chemokine 16 is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of C-X-C motif chemokine 16 generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in C-X-C motif chemokine 16:

Residues Length Domain ID 1-29 29 signal sequence 30-254 225 C-X-C motif chemokine 16 30-205 176 extracellular 206-226  21 transmembrane 227-254  28 cytoplasmic

As used herein, the term “Protein S100-A12” refers to one or more polypeptides present in a biological sample that are derived from the Protein S100-A12 precursor (Swiss-Prot P80511 (SEQ ID NO: 5)).

        10         20         30         40 MTKLEEHLEG IVNIFHQYSV RKGHFDTLSK GELKQLLTKE         50         60         70         80 LANTIKNIKD KAVIDEIFQG LDANQDEQVD FQEFISLVAI         90 ALKAAHYHTH KE

The following domains have been identified in Protein S100-A12:

Residues Length Domain ID 1 1 Initiator methionine 2-92 91 Protein S100-A12

As used herein, the term “Eotaxin” refers to one or more polypeptides present in a biological sample that are derived from the Eotaxin precursor (Swiss-Prot P51671 (SEQ ID NO: 6)).

        10         20         30         40 MKVSAALLWL LLIAAAFSPQ GLAGPASVPT TCCFNLANRK         50         60         70         80 IPLQRLESYR RITSGKCPQK AVIFKTKLAK DICADPKKKW         90 VQDSMKYLDQ KSPTPKP

The following domains have been identified in Eotaxin:

Residues Length Domain ID  1-23 23 Signal peptide 24-97 74 Eotaxin

As used herein, the term “E-selectin” refers to one or more polypeptides present in a biological sample that are derived from the E-selectin precursor (Swiss-Prot P16581 (SEQ ID NO: 7)).

        10         20         30         40 MIASQFLSAL TLVLLIKESG AWSYNTSTEA MTYDEASAYC         50         60         70         80 QQRYTHLVAI QNKEEIEYLN SILSYSPSYY WIGIRKVNNV         90        100        110        120 WVWVGTQKPL TEEAKNWAPG EPNNRQKDED CVEIYIKREK        130        140        150        160 DVGMWNDERC SKKKLALCYT AACTNTSCSG HGECVETINN        170        180        190        200 YTCKCDPGFS GLKCEQIVNC TALESPEHGS LVCSHPLGNF        210        220        230        240 SYNSSCSISC DRGYLPSSME TMQCMSSGEW SAPIPACNVV        250        260        270        280 ECDAVTNPAN GFVECFQNPG SFPWNTTCTF DCEEGFELMG        290        300        310        320 AQSLQCTSSG NWDNEKPTCK AVTCRAVRQP QNGSVRCSHS        330        340        350        360 PAGEFTFKSS CNFTCEEGFM LQGPAQVECT TQGQWTQQIP        370        380        390        400 VCEAFQCTAL SNPERGYMNC LPSASGSFRY GSSCEFSCEQ        410        420        430        440 GFVLKGSKRL QCGPTGEWDN EKPTCEAVRC DAVHQPPKGL        450        460        470        480 VRCAHSPIGE FTYKSSCAFS CEEGFELHGS TQLECTSQGQ        490        500        510        520 WTEEVPSCQV VKCSSLAVPG KINMSCSGEP VFGTVCKFAC        530        540        550        560 PEGWTLNGSA ARTCGATGHW SGLLPTCEAP TESNIPLVAG        570        580        590        600 LSAAGLSLLT LAPFLLWLRK CLRKAKKFVP ASSCQSLESD        610 GSYQKPSYIL

Most preferably, the E-selectin assay detects one or more soluble forms of E-selectin. E-selectin is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of E-selectin generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in E-selectin:

Residues Length Domain ID 1-21 21 signal sequence 22-610 589 E-selectin 22-556 535 extracellular 557-578  22 transmembrane 579-610  32 cytoplasmic

As used herein, the term “Fibronectin” refers to one or more polypeptides present in a biological sample that are derived from the Fibronectin precursor (Swiss-Prot P02751 (SEQ ID NO: 8)).

        10         20         30         40 MLRGPGPGLL LLAVQCLGTA VPSTGASKSK RQAQQMVQPQ         50         60         70         80 SPVAVSQSKP GCYDNGKHYQ INQQWERTYL GNALVCTCYG         90        100        110        120 GSRGFNCESK PEAEETCFDK YTGNTYRVGD TYERPKDSMI        130        140        150        160 WDCTCIGAGR GRISCTIANR CHEGGQSYKI GDTWRRPHET        170        180        190        200 GGYMLECVCL GNGKGEWTCK PIAEKCFDHA AGTSYVVGET        210        220        230        240 WEKPYQGWMM VDCTCLGEGS GRITCTSRNR CNDQDTRTSY        250        260        270        280 RIGDTWSKKD NRGNLLQCIC TGNGRGEWKC ERHTSVQTTS        290        300        310        320 SGSGPFTDVR AAVYQPQPHP QPPPYGHCVT DSGVVYSVGM        330        340        350        360 QWLKTQGNKQ MLCTCLGNGV SCQETAVTQT YGGNSNGEPC        370        380        390        400 VLPFTYNGRT FYSCTTEGRQ DGHLWCSTTS NYEQDQKYSF        410        420        430        440 CTDHTVLVQT QGGNSNGALC HFPFLYNNHN YTDCTSEGRR        450        460        470        480 DNMKWCGTTQ NYDADQKFGF CPMAAHEEIC TTNEGVMYRI        490        500        510        520 GDQWDKQHDM GHMMRCTCVG NGRGEWTCIA YSQLRDQCIV        530        540        550        560 DDITYNVNDT FHKRHEEGHM LNCTCFGQGR GRWKCDPVDQ        570        580        590        600 CQDSETGTFY QIGDSWEKYV HGVRYQCYCY GRGIGEWHCQ        610        620        630        640 PLQTYPSSSG PVEVFITETP SQPNSHPIQW NAPQPSHISK        650        660        670        680 YILRWRPKNS VGRWKEATIP GHLNSYTIKG LKPGVVYEGQ        690        700        710        720 LISIQQYGHQ EVTRFDFTTT STSTPVTSNT VTGETTPFSP        730        740        750        760 LVATSESVTE ITASSFVVSW VSASDTVSGF RVEYELSEEG        770        780        790        800 DEPQYLDLPS TATSVNIPDL LPGRKYIVNV YQISEDGEQS        810        820        830        840 LILSTSQTTA PDAPPDPTVD QVDDTSIVVR WSRPQAPITG        850        860        870        880 YRIVYSPSVE GSSTELNLPE TANSVTLSDL QPGVQYNITI        890        900        910        920 YAVEENQEST PVVIQQETTG TPRSDTVPSP RDLQFVEVTD        930        940        950        960 VKVTIMWTPP ESAVTGYRVD VIPVNLPGEH GQRLPISRNT        970        980        990       1000 FAEVTGLSPG VTYYFKVFAV SHGRESKPLT AQQTTKLDAP       1010       1020       1030       1040 TNLQFVNETD STVLVRWTPP RAQITGYRLT VGLTRRGQPR       1050       1060       1070       1080 QYNVGPSVSK YPLRNLQPAS EYTVSLVAIK GNQESPKATG       1090       1100       1110       1120 VFTTLQPGSS IPPYNTEVTE TTIVITWTPA PRIGFKLGVR       1130       1140       1150       1160 PSQGGEAPRE VTSDSGSIVV SGLTPGVEYV YTIQVLRDGQ       1170       1180       1190       1200 ERDAPIVNKV VTPLSPPTNL HLEANPDTGV LTVSWERSTT       1210       1220       1230       1240 PDITGYRITT TPTNGQQGNS LEEVVHADQS SCTFDNLSPG       1250       1260       1270       1280 LEYNVSVYTV KDDKESVPIS DTIIPAVPPP TDLRFTNIGP       1290       1300       1310       1320 DTMRVTWAPP PSIDLTNFLV RYSPVKNEED VAELSISPSD       1330       1340       1350       1360 NAVVLTNLLP GTEYVVSVSS VYEQHESTPL RGRQKTGLDS       1370       1380       1390       1400 PTGIDFSDIT ANSFTVHWIA PRATITGYRI RHHPEHFSGR       1410       1420       1430       1440 PREDRVPHSR NSITLTNLTP GTEYVVSIVA LNGREESPLL       1450       1460       1470       1480 IGQQSTVSDV PRDLEVVAAT PTSLLISWDA PAVTVRYYRI       1490       1500       1510       1520 TYGETGGNSP VQEFTVPGSK STATISGLKP GVDYTITVYA       1530       1540       1550       1560 VTGRGDSPAS SKPISINYRT EIDKPSQMQV TDVQDNSISV       1570       1580       1590       1600 KWLPSSSPVT GYRVTTTPKN GPGPTKTKTA GPDQTEMTIE       1610       1620       1630       1640 GLQPTVEYVV SVYAQNPSGE SQPLVQTAVT NIDRPKGLAF       1650       1660       1670       1680 TDVDVDSIKI AWESPQGQVS RYRVTYSSPE DGIHELFPAP       1690       1700       1710       1720 DGEEDTAELQ GLRPGSEYTV SVVALHDDME SQPLIGTQST       1730       1740       1750       1760 AIPAPTDLKF TQVTPTSLSA QWTPPNVQLT GYRVRVTPKE       1770       1780       1790       1800 KTGPMKEINL APDSSSVVVS GLMVATKYEV SVYALKDTLT       1810       1820       1830       1840 SRPAQGVVTT LENVSPPRRA RVTDATETTI TISWRTKTET       1850       1860       1870       1880 ITGFQVDAVP ANGQTPIQRT IKPDVRSYTI TGLQPGTDYK       1890       1900       1910       1920 IYLYTLNDNA RSSPVVIDAS TAIDAPSNLR FLATTPNSLL       1930       1940       1950       1960 VSWQPPRARI TGYIIKYEKP GSPPREVVPR PRPGVTEATI       1970       1980       1990       2000 TGLEPGTEYT IYVIALKNNQ KSEPLIGRKK TDELPQLVTL       2010       2020       2030       2040 PHPNLHGPEI LDVPSTVQKT PFVTHPGYDT GNGIQLPGTS       2050       2060       2070       2080 GQQPSVGQQM IFEEHGFRRT TPPTTATPIR HRPRPYPPNV       2090       2100       2110       2120 GEEIQIGHIP REDVDYHLYP HGPGLNPNAS TGQEALSQTT       2130       2140       2150       2160 ISWAPFQDTS EYIISCHPVG TDEEPLQFRV PGTSTSATLT       2170       2180       2190       2200 GLTRGATYNI IVEALKDQQR HKVREEVVTV GNSVNEGLNQ       2210       2220       2230       2240 PTDDSCFDPY TVSHYAVGDE WERMSESGFK LLCQCLGFGS       2250       2260       2270       2280 GHFRCDSSRW CHDNGVNYKI GEKWDRQGEN GQMMSCTCLG       2290       2300       2310       2320 NGKGEFKCDP HEATCYDDGK TYHVGEQWQK EYLGAICSCT       2330       2340       2350       2360 CFGGQRGWRC DNCRRPGGEP SPEGTTGQSY NQYSQRYHQR       2370       2380 TNTNVNCPIE CFMPLDVQAD REDSRE

The following domains have been identified in Fibronectin:

Residues Length Domain ID 1-31 31 Signal peptide  32-2386 2355 Fibronectin

At least 14 other isoforms of Fibronectin are known and are considered “fibronectin” for purposes of the present invention.

As used herein, the term “Granulocyte colony-stimulating factor” refers to one or more polypeptides present in a biological sample that are derived from the Granulocyte colony-stimulating factor precursor (Swiss Prot P09919 (SEQ ID NO: 9)).

        10         20         30         40 MAGPATQSPM KLMALQLLLW HSALWTVQEA TPLGPASSLP         50         60         70         80 QSFLLKCLEQ VRKIQGDGAA LQEKLVSECA TYKLCHPEEL         90        100        110        120 VLLGHSLGIP WAPLSSCPSQ ALQLAGCLSQ LHSGLFLYQG        130        140        150        160 LLQALEGISP ELGPTLDTLQ LDVADFATTI WQQMEELGMA        170        180        190        200 PALQPTQGAM PAFASAFQRR AGGVLVASHL QSFLEVSYRV LRHLAQP

The following domains have been identified in Granulocyte colony-stimulating factor:

Residues Length Domain ID 1-29 29 Signal peptide 30-207 178 Granulocyte colony- stimulating factor

As used herein, the term “Granulocyte-macrophage colony-stimulating factor” refers to one or more polypeptides present in a biological sample that are derived from the Granulocyte-macrophage colony-stimulating factor precursor (Swiss-Prot P04141 (SEQ ID NO: 10)).

        10         20         30         40 MWLQSLLLLG TVACSISAPA RSPSPSTQPW EHVNAIQEAR         50         60         70         80 RLLNLSRDTA AEMNETVEVI SEMFDLQEPT CLQTRLELYK         90        100        110        120 QGLRGSLTKL KGPLTMMASH YKQHCPPTPE TSCATQIITF        130        140 ESFKENLKDF LLVIPFDCWE PVQE

The following domains have been identified in Granulocyte-macrophage colony-stimulating factor:

Residues Length Domain ID 1-17 17 Signal peptide 18-144 127 Granulocyte-macrophage colony-stimulating factor

As used herein, the term “Heparin-binding growth factor 2” refers to one or more polypeptides present in a biological sample that are derived from the Heparin-binding growth factor 2 precursor (Swiss-Prot P09038 (SEQ ID NO: 11)).

        10         20         30         40 MAAGSITTLP ALPEDGGSGA FPPGHFKDPK RLYCKNGGFF         50         60         70         80 LRIHPDGRVD GVREKSDPHI KLQLQAEERG VVSIKGVCAN         90        100        110        120 RYLAMKEDGR LLASKCVTDE CFFFERLESN NYNTYRSRKY        130        140        150 TSWYVALKRT GQYKLGSKTG PGQKAILFLP MSAKS

The following domains have been identified in Heparin-binding growth factor 2:

Residues Length Domain ID 1-9  9 Propeptide 10-155 146 Heparin-binding growth factor 2

As used herein, the term “hepatocyte growth factor receptor” refers to one or more polypeptides present in a biological sample that are derived from the hepatocyte growth factor receptor precursor (Swiss-Prot P08581 (SEQ ID NO: 12)).

        10         20         30         40 MKAPAVLAPG ILVLLFTLVQ RSNGECKEAL AKSEMNVNMK         50         60         70         80 YQLPNFTAET PIQNVILHEH HIFLGATNYI YVLNEEDLQK         90        100        110        120 VAEYKTGPVL EHPDCFPCQD CSSKANLSGG VWKDNINMAL        130        140        150        160 VVDTYYDDQL ISCGSVNRGT CQRHVFPHNH TADIQSEVHC        170        180        190        200 IFSPQIEEPS QCPDCVVSAL GAKVLSSVKD RFINFFVGNT        210        220        230        240 INSSYFPDHP LHSISVRRLK ETKDGFMFLT DQSYIDVLPE        250        260        270        280 FRDSYPIKYV HAFESNNFIY FLTVQRETLD AQTFHTRIIR        290        300        310        320 FCSINSGLHS YMEMPLECIL TEKRKKRSTK KEVFNILQAA        330        340        350        360 YVSKPGAQLA RQIGASLNDD ILFGVFAQSK PDSAEPMDRS        370        380        390        400 AMCAFPIKYV NDFFNKIVNK NNVRCLQHFY GPNHEHCFNR        410        420        430        440 TLLRNSSGCE ARRDEYRTEF TTALQRVDLF MGQFSEVLLT        450        460        470        480 SISTFIKGDL TIANLGTSEG RFMQVVVSRS GPSTPHVNFL        490        500        510        520 LDSHPVSPEV IVEHTLNQNG YTLVITGKKI TKIPLNGLGC        530        540        550        560 RHFQSCSQCL SAPPFVQCGW CHDKCVRSEE CLSGTWTQQI        570        580        590        600 CLPAIYKVFP NSAPLEGGTR LTICGWDFGF RRNNKFDLKK        610        620        630        640 TRVLLGNESC TLTLSESTMN TLKCTVGPAM NKHFNMSIII        650        660        670        680 SNGHGTTQYS TFSYVDPVIT SISPKYGPMA GGTLLTLTGN        690        700        710        720 YLNSGNSRHI SIGGKTCTLK SVSNSILECY TPAQTISTEF        730        740        750        760 AVKLKIDLAN RETSIFSYRE DPIVYEIHPT KSFISGGSTI        770        780        790        800 TGVGKNLNSV SVPRMVINVH EAGRNFTVAC QHRSNSEIIC        810        820        830        840 CTTPSLQQLN LQLPLKTKAF FMLDGILSKY FDLIYVHNPV        850        860        870        880 FKPFEKPVMI SMGNENVLEI KGNDIDPEAV KGEVLKVGNK        890        900        910        920 SCENIHLHSE AVLCTVPNDL LKLNSELNIE WKQAISSTVL        930        940        950        960 GKVIVQPDQN FTGLIAGVVS ISTALLLLLG FFLWLKKRKQ        970        980        990       1000 IKDLGSELVR YDARVHTPHL DRLVSARSVS PTTEMVSNES       1010       1020       1030       1040 VDYRATFPED QFPNSSQNGS CRQVQYPLTD MSPILTSGDS       1050       1060       1070       1080 DISSPLLQNT VHIDLSALNP ELVQAVQHVV IGPSSLIVHF       1090       1100       1110       1120 NEVIGRGHFG CVYHGTLLDN DGKKIHCAVK SLNRITDIGE       1130       1140       1150       1160 VSQFLTEGII MKDFSHPNVL SLLGICLRSE GSPLVVLPYM       1170       1180       1190       1200 KHGDLRNFIR NETHNPTVKD LIGFGLQVAK GMKYLASKKF       1210       1220       1230       1240 VHRDLAARNC MLDEKFTVKV ADFGLARDMY DKEYYSVHNK       1250       1260       1270       1280 TGAKLPVKWM ALESLQTQKF TTKSDVWSFG VVLWELMTRG       1290       1300       1310       1320 APPYPDVNTF DITVYLLQGR RLLQPEYCPD PLYEVMLKCW       1330       1340       1350       1360 HPKAEMRPSF SELVSRISAI FSTFIGEHYV HVNATYVNVK       1370       1380       1390 CVAPYPSLLS SEDNADDEVD TRPASFWETS

Most preferably, the hepatocyte growth factor receptor assay detects one or more soluble forms of hepatocyte growth factor receptor. Hepatocyte growth factor receptor is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of hepatocyte growth factor receptor generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in hepatocyte growth factor receptor:

Residues Length Domain ID 1-24 24 signal sequence  25-1390 1366 hepatocyte growth factor receptor 25-932 908 extracellular 933-955  23 transmembrane 956-1390 435 cytoplasmic

As used herein, the term “Interleukin-1 receptor antagonist protein” refers to one or more polypeptides present in a biological sample that are derived from the Interleukin-1 receptor antagonist protein precursor (Swiss-Prot P18510 (SEQ ID NO: 13)).

        10         20         30         40 MEICRGLRSH LITLLLFLFH SETICRPSGR KSSKMQAFRI         50         60         70         80 WDVNQKTFYL RNNQLVAGYL QGPNVNLEEK IDVVPIEPHA         90        100        110        120 LFLGIHGGKM CLSCVKSGDE TRLQLEAVNI TDLSENRKQD        130        140        150        160 KRFAFIRSDS GPTTSFESAA CPGWFLCTAM EADQPVSLTN        170 MPDEGVMVTK FYFQEDE

The following domains have been identified in Interleukin-1 receptor antagonist protein:

Residues Length Domain ID 1-25 25 Signal peptide 26-177 152 Interleukin-1 receptor antagonist protein

In addition, three variant isoforms of Interleukin-1 receptor antagonist protein are known. Isoform 2 replaces residues 1-21 with MAL; isoform 3 replaces residues 1-21 with MALADLYEEGGGGGGEGEDNADSK (SEQ ID NO: 33); and isoform 4 lacks residues 1-34.

As used herein, the term “Interleukin-1 beta” refers to one or more polypeptides present in a biological sample that are derived from the Interleukin-1 beta precursor (Swiss-Prot P01584 (SEQ ID NO: 14)).

        10         20         30         40 MAEVPELASE MMAYYSGNED DLFFEADGPK QMKCSFQDLD         50         60         70         80 LCPLDGGIQL RISDHHYSKG FRQAASVVVA MDKLRKMLVP         90        100        110        120 CPQTFQENDL STFFPFIFEE EPIFFDTWDN EAYVHDAPVR        130        140        150        160 SLNCTLRDSQ QKSLVMSGPY ELKALHLQGQ DMEQQVVFSM        170        180        190        200 SFVQGEESND KIPVALGLKE KNLYLSCVLK DDKPTLQLES        210        220        230        240 VDPKNYPKKK MEKRFVFNKI EINNKLEFES AQFPNWYIST        250        260        SQAENMPVFL GGTKGGQDIT DFTMQFVSS

The following domains have been identified in Interleukin-1 beta:

Residues Length Domain ID  1-116 116 Propeptide 117-269 153 Interleukin-1 beta

As used herein, the term “Interleukin-10” refers to one or more polypeptides present in a biological sample that are derived from the Interleukin-10 precursor (Swiss-Prot P22301 (SEQ ID NO: 15)).

        10         20         30         40 MHSSALLCCL VLLTGVRASP GQGTQSENSC THFPGNLPNM         50         60         70         80 LRDLRDAFSR VKTFFQMKDQ LDNLLLKESL LEDFKGYLGC         90        100        110        120 QALSEMIQFY LEEVMPQAEN QDPDIKAHVN SLGENLKTLR        130        140        150        160 LRLRRCHRFL PCENKSKAVE QVKNAFNKLQ EKGIYKAMSE        170 FDIFINYIEA YMTMKIRN

The following domains have been identified in Interleukin-10:

Residues Length Domain ID 1-18 18 Signal peptide 19-178 160 Interleukin-10

As used herein, the term “Interleukin-15” refers to one or more polypeptides present in a biological sample that are derived from the Interleukin-15 precursor (Swiss-Prot P40933 (SEQ ID NO: 16)).

        10         20         30         40 MRISKPHLRS ISIQCYLCLL LNSHFLTEAG IHVFILGCFS         50         60         70         80 AGLPKTEANW VNVISDLKKI EDLIQSMHID ATLYTESDVH         90        100        110        120 PSCKVTAMKC FLLELQVISL ESGDASIHDT VENLIILANN        130        140        150        160 SLSSNGNVTE SGCKECEELE EKNIKEFLQS FVHIVQMFIN TS

The following domains have been identified in Interleukin-15:

Residues Length Domain ID 1-29 29 Signal peptide 30-48  19 Propeptide 49-162 114 Interleukin-15

In addition, two variant Interleukin-15 isoforms are known. Isoform 2 replaces residues 1-37 with MVLGTIDLCS (SEQ ID NO: 17; and isoform 3 replaces residues 1-47 with MDFQVQIFSFLLISASVIMSR (SEQ ID NO: 18).

As used herein, the term “Interleukin-3” refers to one or more polypeptides present in a biological sample that are derived from the Interleukin-3 precursor (Swiss-Prot P08700 (SEQ ID NO: 19)).

        10         20         30         40 MSRLPVLLLL QLLVRPGLQA PMTQTTPLKT SWVNCSNMID         50         60         70         80 EIITHLKQPP LPLLDFNNLN GEDQDILMEN NLRRPNLEAF         90        100        110        120 NRAVKSLQNA SAIESILKNL LPCLPLATAA PTRHPIHIKD        130        140        150 GDWNEFRRKL TFYLKTLENA QAQQTTLSLA IF

The following domains have been identified in Interleukin-3:

Residues Length Domain ID 1-19 19 Signal peptide 20-152 133 Interleukin-3

As used herein, the term “Myeloperoxidase” refers to one or more polypeptides present in a biological sample that are derived from the Myeloperoxidase precursor (Swiss-Prot P05164 (SEQ ID NO: 20)).

        10         20         30         40 MGVPFFSSLR CMVDLGPCWA GGLTAEMKLL LALAGLLAIL         50         60         70         80 ATPQPSEGAA PAVLGEVDTS LVLSSMEEAK QLVDKAYKER         90        100        110        120 RESIKQRLRS GSASPMELLS YFKQPVAATR TAVRAADYLH        130        140        150        160 VALDLLERKL RSLWRRPFNV TDVLTPAQLN VLSKSSGCAY        170        180        190        200 QDVGVTCPEQ DKYRTITGMC NNRRSPTLGA SNRAFVRWLP         210        220        230        240 AEYEDGFSLP YGWTPGVKRN GFPVALARAV SNEIVRFPTD        250        260        270        280 QLTPDQERSL MFMQWGQLLD HDLDFTPEPA ARASFVTGVN        290        300        310        320 CETSCVQQPP CFPLKIPPND PRIKNQADCI PFFRSCPACP        330        340        350        360 GSNITIRNQI NALTSFVDAS MVYGSEEPLA RNLRNMSNQL        370        380        390        400 GLLAVNQRFQ DNGRALLPFD NLHDDPCLLT NRSARIPCFL        410        420        430        440 AGDTRSSEMP ELTSMHTLLL REHNRLATEL KSLNPRWDGE        450        460        470        480 RLYQEARKIV GAMVQIITYR DYLPLVLGPT AMRKYLPTYR        490        500        510        520 SYNDSVDPRI ANVFTNAFRY GHTLIQPFMF RLDNRYQPME        530        540        550        560 PNPRVPLSRV FFASWRVVLE GGIDPILRGL MATPAKLNRQ        570        580        590        600 NQIAVDEIRE RLFEQVMRIG LDLPALNMQR SRDHGLPGYN        610        620        630        640 AWRRFCGLPQ PETVGQLGTV LRNLKLARKL MEQYGTPNNI        650        660        670        680 DIWMGGVSEP LKRKGRVGPL LACIIGTQFR KLRDGDRFWW        690        700        710        720 ENEGVFSMQQ RQALAQISLP RIICDNTGIT TVSKNNIFMS        730        740 NSYPRDFVNC STLPALNLAS WREAS

The following domains have been identified in Myeloperoxidase:

Residues Length Domain ID  1-48 48 Signal peptide  49-745 697 89 kDa Myeloperoxidase  49-164 116 propeptide 155-745 591 84 kDa Myeloperoxidase 165-278 114 Myeloperoxidase light chain 279-745 467 Myeloperoxidase heavy chain

As used herein, the term “Nidogen-1” refers to one or more polypeptides present in a biological sample that are derived from the Nidogen-1 precursor (Swiss-Prot P14543 (SEQ ID NO: 21)).

        10         20         30         40 MLASSSRIRA AWTRALLLPL LLAGPVGCLS RQELFPFGPG         50         60         70         80 QGDLELEDGD DFVSPALELS GALRFYDRSD IDAVYVTTNG         90        100        110        120 IIATSEPPAK ESHPGLFPPT FGAVAPFLAD LDTTDGLGKV        130        140        150        160 YYREDLSPSI TQRAAECVHR GFPEISFQPS SAVVVTWESV        170        180        190        200 APYQGPSRDP DQKGKRNTFQ AVLASSDSSS YAIFLYPEDG        210        220        230        240 LQFHTTFSKK ENNQVPAVVA FSQGSVGFLW KSNGAYNIFA        250        260        270        280 NDRESIENLA KSSNSGQQGV WVFEIGSPAT TNGVVPADVI        290        300        310        320 LGTEDGAEYD DEDEDYDLAT TRLGLEDVGT TPFSYKALRR        330        340        350        360 GGADTYSVPS VLSPRRAATE RPLGPPTERT RSFQLAVETF        370        380        390        400 HQQHPQVIDV DEVEETGVVF SYNTDSRQTC ANNRHQCSVH        410        420        430        440 AECRDYATGF CCSCVAGYTG NGRQCVAEGS PQRVNGKVKG        450        460        470        480 RIFVGSSQVP IVFENTDLHS YVVMNHGRSY TAISTIPETV        490        500        510        520 GYSLLPLAPV GGIIGWMFAV EQDGFKNGFS ITGGEFTRQA        530        540        550        560 EVTFVGHPGN LVIKQRFSGI DEHGHLTIDT ELEGRVPQIP        570        580        590        600 FGSSVHIEPY TELYHYSTSV ITSSSTREYT VTEPERDGAS        610        620        630        640 PSRIYTYQWR QTITFQECVH DDSRPALPST QQLSVDSVFV        650        660        670        680 LYNQEEKILR YAFSNSIGPV REGSPDALQN PCYIGTHGCD        690        700        710        720 TNAACRPGPR TQFTCECSIG FRGDGRTCYD IDECSEQPSV        730        740        750        760 CGSHTICNNH PGTFRCECVE GYQFSDEGTC VAVVDQRPIN        770        780        790        800 YCETGLHNCD IPQRAQCIYT GGSSYTCSCL PGFSGDGQAC        810        820        830        840 QDVDECQPSR CHPDAFCYNT PGSFTCQCKP GYQGDGFRCV        850        860        870        880 PGEVEKTRCQ HEREHILGAA GATDPQRPIP PGLFVPECDA        890        900        910        920 HGHYAPTQCH GSTGYCWCVD RDGREVEGTR TRPGMTPPCL        930        940        950        960 STVAPPIHQG PAVPTAVIPL PPGTHLLFAQ TGKIERLPLE        970        980        990       1000 GNTMRKTEAK AFLHVPAKVI IGLAFDCVDK MVYWTDITEP       1010       1020       1030       1040 SIGRASLHGG EPTTIIRQDL GSPEGIAVDH LGRNIFWTDS       1050       1060       1070       1080 NLDRIEVAKL DGTQRRVLFE TDLVNPRGIV TDSVRGNLYW       1090       1100       1110       1120 TDWNRDNPKI ETSYMDGTNR RILVQDDLGL PNGLTFDAFS       1130       1140       1150       1160 SQLCWVDAGT NRAECLNPSQ PSRRKALEGL QYPFAVTSYG       1170       1180       1190       1200 KNLYFTDWKM NSVVALDLAI SKETDAFQPH KQTRLYGITT       1210       1220       1230       1240 ALSQCPQGHN YCSVNNGGCT HLCLATPGSR TCRCPDNTLG VDCIERK

The following domains have been identified in Nidogen-1:

Residues Length Domain ID 1-28  28 signal sequence 29-1247 1219 Nidogen-1

As used herein, the term “oxidized low-density lipoprotein receptor 1” refers to one or more polypeptides present in a biological sample that are derived from the oxidized low-density lipoprotein receptor 1 precursor (Swiss-Prot P78380 (SEQ ID NO: 22)).

        10         20         30         40     MTFDDLKIQT VKDQPDEKSN GKKAKGLQFL YSPWWCLAAA         50         60         70         80 TLGVLCLGLV VTIMVLGMQL SQVSDLLTQE QANLTHQKKK         90        100        110        120 LEGQISARQQ AEEASQESEN ELKEMIETLA RKLNEKSKEQ        130        140        150        160    MELHHQNLNL QETLKRVANC SAPCPQDWIW HGENCYLFSS        170        180        190        200    GSFNWEKSQE KCLSLDAKLL KINSTADLDF IQQAISYSSF        210        220        230        240 PFWMGLSRRN PSYPWLWEDG SPLMPHLFRV RGAVSQTYPS        250        260        270 GTCAYIQRGA VYAENCILAA FSICQKKANL RAQ

Most preferably, the oxidized low-density lipoprotein receptor 1 assay detects one or more soluble forms of oxidized low-density lipoprotein receptor 1. Oxidized low-density lipoprotein receptor 1 is a single-pass type II membrane protein having a large extracellular domain, most or all of which is present in soluble forms of oxidized low-density lipoprotein receptor 1 generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in oxidized low-density lipoprotein receptor 1:

Residues Length Domain ID  1-273 273 oxidized low-density lipoprotein receptor 1, membrane bound form 1-36 36 cytoplasmic 37-57  21 membrane anchor signal 58-273 216 extracellular

As used herein, the term “Pappalysin-1” refers to one or more polypeptides present in a biological sample that are derived from the Pappalysin-1 precursor (Swiss-Prot Q13219 (SEQ ID NO: 23)).

        10         20         30         40 MRLWSWVLHL GLLSAALGCG LAERPRRARR DPRAGRPPRP         50         60         70         80 AAGPATCATR AARGRRASPP PPPPPGGAWE AVRVPRRRQQ         90        100        110        120 REARGATEEP SPPSRALYFS GRGEQLRVLR ADLELPRDAF        130        140        150        160 TLQVWLRAEG GQRSPAVITG LYDKCSYISR DRGWVVGIHT        170        180        190        200 ISDQDNKDPR YFFSLKTDRA RQVTTINAHR SYLPGQWVYL        210        220        230        240 AATYDGQFMK LYVNGAQVAT SGEQVGGIFS PLTQKCKVLM        250        260        270        280 LGGSALNHNY RGYIEHFSLW KVARTQREIL SDMETHGAHT        290        300        310        320 ALPQLLLQEN WDNVKHAWSP MKDGSSPKVE FSNAHGFLLD        330        340        350        360 TSLEPPLCGQ TLCDNTEVIA SYNQLSSFRQ PKVVRYRVVN        370        380        390        400 LYEDDHKNPT VTREQVDFQH HQLAEAFKQY NISWELDVLE        410        420        430        440 VSNSSLRRRL ILANCDISKI GDENCDPECN HTLTGHDGGD        450        460        470        480 CRHLRHPAFV KKQHNGVCDM DCNYERFNFD GGECCDPEIT        490        500        510        520 NVTQTCFDPD SPHRAYLDVN ELKNILKLDG STHLNIFFAK        530        540        550        560 SSEEELAGVA TWPWDKEALM HLGGIVLNPS FYGMPGHTHT        570        580        590        600 MIHEIGHSLG LYHVFRGISE IQSCSDPCME TEPSFETGDL        610        620        630        640 CNDTNPAPKH KSCGDPGPGN DTCGFHSFFN TPYNNFMSYA        650        660        670        680 DDDCTDSFTP NQVARMHCYL DLVYQGWQPS RKPAPVALAP        690        700        710        720 QVLGHTTDSV TLEWFPPIDG HFFERELGSA CHLCLEGRIL        730        740        750        760  VQYASNASSP MPCSPSGHWS PREAEGHPDV EQPCKSSVRT        770        780        790        800 WSPNSAVNPH TVPPACPEPQ GCYLELEFLY PLVPESLTIW        810        820        830        840 VTFVSTDWDS SGAVNDIKLL AVSGKNISLG PQNVFCDVPL        850        860        870        880 TIRLWDVGEE VYGIQIYTLD EHLEIDAAML TSTADTPLCL        890        900        910        920 QCKPLKYKVV RDPPLQMDVA SILHLNRKFV DMDLNLGSVY        930        940        950        960 QYWVITISGT EESEPSPAVT YIHGRGYCGD GIIQKDQGEQ        970        980        990       1000 CDDMNKINGD GCSLFCRQEV SFNCIDEPSR CYFHDGDGVC       1010       1020       1030       1040 EEFEQKTSIK DCGVYTPQGF LDQWASNASV SHQDQQCPGW       1050       1060       1070       1080 VIIGQPAASQ VCRTKVIDLS EGISQHAWYP CTISYPYSQL       1090       1100       1110       1120 AQTTFWLRAY FSQPMVAAAV IVHLVTDGTY YGDQKQETIS       1130       1140       1150       1160 VQLLDTKDQS HDLGLHVLSC RNNPLIIPVV HDLSQPFYHS       1170       1180       1190       1200 QAVRVSFSSP LVAISGVALR SFDNFDPVTL SSCQRGETYS       1210       1220       1230       1240 PAEQSCVHFA CEKTDCPELA VENASLNCSS SDRYHGAQCT       1250       1260       1270       1280 VSCRTGYVLQ IRRDDELIKS QTGPSVTVTC TEGKWNKQVA       1290       1300       1310       1320 CEPVDCSIPD HHQVYAASFS CPEGTTFGSQ CSFQCRHPAQ       1330       1340       1350       1360 LKGNNSLLTC MEDGLWSFPE ALCELMCLAP PPVPNADLQT       1370       1380       1390       1400 ARCRENKHKV GSFCKYKCKP GYHVPGSSRK SKKRAFKTQC       1410       1420       1430       1440 TQDGSWQEGA CVPVTCDPPP PKFHGLYQCT NGFQFNSECR       1450       1460       1470       1480 IKCEDSDASQ GLGSNVIHCR KDGTWNGSFH VCQEMQGQCS       1490       1500       1510       1520 VPNELNSNLK LQCPDGYAIG SECATSCLDH NSESIILPMN       1530       1540       1550       1560 VTVRDIPHWL NPTRVERVVC TAGLKWYPHP ALIHCVKGCE       1570       1580       1590       1600 PFMGDNYCDA INNRAFCNYD GGDCCTSTVK TKKVTPFPMS       1610       1620 CDLQGDCACR DPQAQEHSRK DLRGYSHG

The following domains have been identified in Pappalysin-1:

Residues Length Domain ID 1-22 22 Signal peptide 23-80  58 Propeptide  81-1628 1548 Pappalysin-1

As used herein, the term “P-selectin glycoprotein ligand 1” refers to one or more polypeptides present in a biological sample that are derived from the P-selectin glycoprotein ligand 1 precursor (Swiss-Prot Q14242 (SEQ ID NO: 24)).

        10         20         30         40  MPLQLLLLLI LLGPGNSLQL WDTWADEAEK ALGPLLARDR         50         60         70         80  RQATEYEYLD YDFLPETEPP EMLRNSTDTT PLTGPGTPES         90        100        110        120 TTVEPAARRS TGLDAGGAVT ELTTELANMG NLSTDSAAME        130        140        150        160  IQTTQPAATE AQTTQPVPTE AQTTPLAATE AQTTRLTATE        170        180        190        200  AQTTPLAATE AQTTPPAATE AQTTQPTGLE AQTTAPAAME        210        220        230        240 AQTTAPAAME AQTTPPAAME AQTTQTTAME AQTTAPEATE        250        260        270        280  AQTTQPTATE AQTTPLAAME ALSTEPSATE ALSMEPTTKR        290        300        310        320  GLFIPFSVSS VTHKGIPMAA SNLSVNYPVG APDHISVKQC        330        340        350        360 LLAILILALV ATIFFVCTVV LAVRLSRKGH MYPVRNYSPT        370        380        390        400  EMVCISSLLP DGGEGPSATA NGGLSKAKSP GLTPEPREDR        410 EGDDLTLHSF LP

Most preferably, the P-selectin glycoprotein ligand 1 assay detects one or more soluble forms of P-selectin glycoprotein ligand 1. P-selectin glycoprotein ligand 1 is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of P-selectin glycoprotein ligand 1 generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in P-selectin glycoprotein ligand 1:

Residues Length Domain ID  1-17 17 signal sequence 18-41 24 propeptide  42-412 371 P-selectin glycoprotein ligand 1  18-320 303 extracellular 321-341 21 transmembrane 342-412 71 cytoplasmic

As used herein, the term “Antileukoproteinase” refers to one or more polypeptides present in a biological sample that are derived from the Antileukoproteinase precursor (Swiss-Prot P03973 (SEQ ID NO: 25)).

        10         20         30         40 MKSSGLFPFL VLLALGTLAP WAVEGSGKSF KAGVCPPKKS         50         60         70         80 AQCLRYKKPE CQSDWQCPGK KRCCPDTCGI KCLDPVDTPN         90        100        110        120 PTRRKPGKCP VTYGQCLMLN PPNFCEMDGQ CKRDLKCCMG        130 MCGKSCVSPV KA

The following domains have been identified in Antileukoproteinase:

Residues Length Domain ID 1-25 25 signal sequence 26-132 107 Antileukoproteinase

As used herein, the term “Kit ligand” refers to one or more polypeptides present in a biological sample that are derived from the Kit ligand precursor (Swiss-Prot P21583 (SEQ ID NO: 26)).

        10         20         30         40 MKKTQTWILT CIYLQLLLFN PLVKTEGICR NRVTNNVKDV         50         60         70         80 TKLVANLPKD YMITLKYVPG MDVLPSHCWI SEMVVQLSDS         90        100        110        120 LTDLLDKFSN ISEGLSNYSI IDKLVNIVDD LVECVKENSS        130        140        150        160 KDLKKSFKSP EPRLFTPEEF FRIFNRSIDA FKDFVVASET        170        180        190        200 SDCVVSSTLS PEKDSRVSVT KPFMLPPVAA SSLRNDSSSS        210        220        230        240 NRKAKNPPGD SSLHWAAMAL PALFSLIIGF AFGALYWKKR        250        260        270 QPSLTRAVEN IQINEEDNEI SMLQEKEREF QEV In addition, a soluble splice variant form of Kit ligand has been described (SEQ ID NO:27):

        10         20         30         40  MKKTQTWILT CIYLQLLLFN PLVKTEGICR NRVTNNVKDV         50         60         70         80  TKLVANLPKD YMITLKYVPG MDVLPSHCWI SEMVVQLSDS         90        100        110        120 LTDLLDKFSN ISEGLSNYSI IDKLVNIVDD LVECVKENSS        130        140        150        160  KDLKKSFKSP EPRLFTPEEF FRIFNRSIDA FKDFVVASET        170        180        190        200 SDCVVSSTLS PEKGKAKNPP GDSSLHWAAM ALPALFSLII        210        220        230        240 GFAFGALYWK KRQPSLTRAV ENIQINEEDN EISMLQEKER EFQEV

Most preferably, the Kit ligand assay detects one or more soluble forms of Kit ligand. Kit ligand is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of Kit ligand generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in Kit ligand:

Residues Length Domain ID 1-25 25 signal sequence 26-273 248 Kit ligand 26-214 189 extracellular 215-237  23 transmembrane 238-273  36 cytoplasmic

As used herein, the term “Metalloproteinase inhibitor 1” refers to one or more polypeptides present in a biological sample that are derived from the Metalloproteinase inhibitor 1 precursor (Swiss-Prot P01033 (SEQ ID NO: 28)).

        10         20         30         40 MAPFEPLASG ILLLLWLIAP SRACTCVPPH PQTAFCNSDL         50         60         70         80 VIRAKFVGTP EVNQTTLYQR YEIKMTKMYK GFQALGDAAD         90        100        110        120 IRFVYTPAME SVCGYFHRSH NRSEEFLIAG KLQDGLLHIT        130        140        150        160 TCSFVAPWNS LSLAQRRGFT KTYTVGCEEC TVFPCLSIPC        170        180        190        200 KLQSGTHCLW TDQLLQGSEK GFQSRHLACL PREPGLCTWQ SLRSQIA

The following domains have been identified in Metalloproteinase inhibitor 1:

Residues Length Domain ID 1-18 23 signal sequence 24-207 184 Metalloproteinase inhibitor 1

As used herein, the term “Metalloproteinase inhibitor 2” refers to one or more polypeptides present in a biological sample that are derived from the Metalloproteinase inhibitor 2 precursor (Swiss-Prot P16035 (SEQ ID NO: 29)).

        10         20         30         40    MGAAARTLRL ALGLLLLATL LRPADACSCS PVHPQQAFCN         50         60         70         80 ADVVIRAKAV SEKEVDSGND IYGNPIKRIQ YEIKQIKMFK         90        100        110        120 GPEKDIEFIY TAPSSAVCGV SLDVGGKKEY LIAGKAEGDG        130        140        150        160 KMHITLCDFI VPWDTLSTTQ KKSLNHRYQM GCECKITRCP        170        180        190        200 MIPCYISSPD ECLWMDWVTE KNINGHQAKF FACIKRSDGS        210        220 CAWYRGAAPP KQEFLDIEDP

The following domains have been identified in Metalloproteinase inhibitor 2:

Residues Length Domain ID 1-26 26 Signal peptide 27-220 194 Metalloproteinase inhibitor 2

As used herein, the term “Tumor necrosis factor” refers to one or more polypeptides present in a biological sample that are derived from the Tumor necrosis factor precursor (Swiss-Prot P01375 (SEQ ID NO: 30)).

        10         20         30         40    MSTESMIRDV ELAEEALPKK TGGPQGSRRC LFLSLFSFLI         50         60         70         80 VAGATTLFCL LHFGVIGPQR EEFPRDLSLI SPLAQAVRSS         90        100        110        120 SRTPSDKPVA HVVANPQAEG QLQWLNRRAN ALLANGVELR        130        140        150        160  DNQLVVPSEG LYLIYSQVLF KGQGCPSTHV LLTHTISRIA        170        180        190        200 VSYQTKVNLL SAIKSPCQRE TPEGAEAKPW YEPIYLGGVF        210        220        230 QLEKGDRLSA EINRPDYLDF AESGQVYFGI IAL

Most preferably, the Tumor necrosis factor assay detects one or more soluble forms of Tumor necrosis factor. Tumor necrosis factor is a single-pass type II membrane protein having a large extracellular domain, some or all of which is present in soluble forms of Tumor necrosis factor generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in Tumor necrosis factor:

Residues Length Domain ID  1-233 233 Tumor necrosis factor, membrane form 77-233 157 Tumor necrosis factor, soluble form 36-56  35 Anchor signal 57-233 177 extracellular 1-35 35 cytoplasmic

As used herein, the term “Vascular cell adhesion molecule 1” refers to one or more polypeptides present in a biological sample that are derived from the Vascular cell adhesion molecule 1 precursor (Swiss-Prot P19320 (SEQ ID NO: 31)).

        10         20         30         40    MPGKMVVILG ASNILWIMFA ASQAFKIETT PESRYLAQIG         50         60         70         80 DSVSLTCSTT GCESPFFSWR TQIDSPLNGK VTNEGTTSTL         90        100        110        120 TMNPVSFGNE HSYLCTATCE SRKLEKGIQV EIYSFPKDPE        130        140        150        160   IHLSGPLEAG KPITVKCSVA DVYPFDRLEI DLLKGDHLMK        170        180        190        200 SQEFLEDADR KSLETKSLEV TFTPVIEDIG KVLVCRAKLH        210        220        230        240 IDEMDSVPTV RQAVKELQVY ISPKNTVISV NPSTKLQEGG        250        260        270        280    SVTMTCSSEG LPAPEIFWSK KLDNGNLQHL SGNATLTLIA        290        300        310        320   MRMEDSGIYV CEGVNLIGKN RKEVELIVQE KPFTVEISPG         330        340        350        360 PRIAAQIGDS VMLTCSVMGC ESPSFSWRTQ IDSPLSGKVR        370        380        390        400   SEGTNSTLTL SPVSFENEHS YLCTVTCGHK KLEKGIQVEL        410        420        430        440  YSFPRDPEIE MSGGLVNGSS VTVSCKVPSV YPLDRLEIEL        450        460        470        480 LKGETILENI EFLEDTDMKS LENKSLEMTF IPTIEDTGKA        490        500        510        520 LVCQAKLHID DMEFEPKQRQ STQTLYVNVA PRDTTVLVSP        530        540        550        560 SSILEEGSSV NMTCLSQGFP APKILWSRQL PNGELQPLSE        570        580        590        600 NATLTLISTK MEDSGVYLCE GINQAGRSRK EVELIIQVTP        610        620        630        640 KDIKLTAFPS ESVKEGDTVI ISCTCGNVPE TWIILKKKAE        650        660        670        680  TGDTVLKSID GAYTIRKAQL KDAGVYECES KNKVGSQLRS        690        700        710        720   LTLDVQGREN NKDYFSPELL VLYFASSLII PAIGMIIYFA        730 RKANMKGSYS LVEAQKSKV

Most preferably, the Vascular cell adhesion molecule 1 assay detects one or more soluble forms of Vascular cell adhesion molecule 1. Vascular cell adhesion molecule 1 is a single-pass type I membrane protein having a large extracellular domain, most or all of which is present in soluble forms of Vascular cell adhesion molecule 1 generated either through alternative splicing event which deletes all or a portion of the transmembrane domain, or by proteolysis of the membrane-bound form. In the case of an immunoassay, one or more antibodies that bind to epitopes within this extracellular domain may be used to detect these soluble form(s). The following domains have been identified in Vascular cell adhesion molecule 1:

Residues Length Domain ID 1-24 24 signal sequence 25-739 715 Vascular cell adhesion molecule 1 25-698 674 extracellular 699-720  22 transmembrane 721-739  19 cytoplasmic

As used herein, the term “Vascular endothelial growth factor A” refers to one or more polypeptides present in a biological sample that are derived from the Vascular endothelial growth factor A precursor (Swiss-Prot P15692 (SEQ ID NO: 32)).

        10         20         30         40    MNFLLSWVHW SLALLLYLHH AKWSQAAPMA EGGGQNHHEV         50         60         70         80 VKFMDVYQRS YCHPIETLVD IFQEYPDEIE YIFKPSCVPL         90        100        110        120 MRCGGCCNDE GLECVPTEES NITMQIMRIK PHQGQHIGEM        130        140        150        160   SFLQHNKCEC RPKKDRARQE KKSVRGKGKG QKRKRKKSRY        170        180        190        200  KSWSVYVGAR CCLMPWSLPG PHPCGPCSER RKHLFVQDPQ        210        220        230 TCKCSCKNTD SRCKARQLEL NERTCRCDKP RR

The following domains have been identified in Vascular endothelial growth factor A:

Residues Length Domain ID 1-26 26 Signal peptide 27-232 483 Vascular endothelial growth factor A In addition, nine other variant forms of Vascular endothelial growth factor A are known, and are considered Vascular endothelial growth factor A for purposes of the present invention. These are VEGF189, VEGF183, VEGF165, VEGF148, VEGF145, VEGF121, VEGF165B, VEGF121B, and VEGF111.

As used herein, the term “relating a signal to the presence or amount” of an analyte reflects this understanding. Assay signals are typically related to the presence or amount of an analyte through the use of a standard curve calculated using known concentrations of the analyte of interest. As the term is used herein, an assay is “configured to detect” an analyte if an assay can generate a detectable signal indicative of the presence or amount of a physiologically relevant concentration of the analyte. Because an antibody epitope is on the order of 8 amino acids, an immunoassay configured to detect a marker of interest will also detect polypeptides related to the marker sequence, so long as those polypeptides contain the epitope(s) necessary to bind to the antibody or antibodies used in the assay. The term “related marker” as used herein with regard to a biomarker such as one of the kidney injury markers described herein refers to one or more fragments, variants, etc., of a particular marker or its biosynthetic parent that may be detected as a surrogate for the marker itself or as independent biomarkers. The term also refers to one or more polypeptides present in a biological sample that are derived from the biomarker precursor complexed to additional species, such as binding proteins, receptors, heparin, lipids, sugars, etc.

The term “positive going” marker as that term is used herein refer to a marker that is determined to be elevated in subjects suffering from a disease or condition, relative to subjects not suffering from that disease or condition. The term “negative going” marker as that term is used herein refer to a marker that is determined to be reduced in subjects suffering from a disease or condition, relative to subjects not suffering from that disease or condition.

The term “subject” as used herein refers to a human or non-human organism. Thus, the methods and compositions described herein are applicable to both human and veterinary disease. Further, while a subject is preferably a living organism, the invention described herein may be used in post-mortem analysis as well. Preferred subjects are humans, and most preferably “patients,” which as used herein refers to living humans that are receiving medical care for a disease or condition. This includes persons with no defined illness who are being investigated for signs of pathology.

Preferably, an analyte is measured in a sample. Such a sample may be obtained from a subject, or may be obtained from biological materials intended to be provided to the subject. For example, a sample may be obtained from a kidney being evaluated for possible transplantation into a subject, and an analyte measurement used to evaluate the kidney for preexisting damage. Preferred samples are body fluid samples.

The term “body fluid sample” as used herein refers to a sample of bodily fluid obtained for the purpose of diagnosis, prognosis, classification or evaluation of a subject of interest, such as a patient or transplant donor. In certain embodiments, such a sample may be obtained for the purpose of determining the outcome of an ongoing condition or the effect of a treatment regimen on a condition. Preferred body fluid samples include blood, serum, plasma, cerebrospinal fluid, urine, saliva, sputum, and pleural effusions. In addition, one of skill in the art would realize that certain body fluid samples would be more readily analyzed following a fractionation or purification procedure, for example, separation of whole blood into serum or plasma components.

The term “diagnosis” as used herein refers to methods by which the skilled artisan can estimate and/or determine the probability (“a likelihood”) of whether or not a patient is suffering from a given disease or condition. In the case of the present invention, “diagnosis” includes using the results of an assay, most preferably an immunoassay, for a kidney injury marker of the present invention, optionally together with other clinical characteristics, to arrive at a diagnosis (that is, the occurrence or nonoccurrence) of an acute renal injury or ARF for the subject from which a sample was obtained and assayed. That such a diagnosis is “determined” is not meant to imply that the diagnosis is 100% accurate. Many biomarkers are indicative of multiple conditions. The skilled clinician does not use biomarker results in an informational vacuum, but rather test results are used together with other clinical indicia to arrive at a diagnosis. Thus, a measured biomarker level on one side of a predetermined diagnostic threshold indicates a greater likelihood of the occurrence of disease in the subject relative to a measured level on the other side of the predetermined diagnostic threshold.

Similarly, a prognostic risk signals a probability (“a likelihood”) that a given course or outcome will occur. A level or a change in level of a prognostic indicator, which in turn is associated with an increased probability of morbidity (e.g., worsening renal function, future ARF, or death) is referred to as being “indicative of an increased likelihood” of an adverse outcome in a patient.

Marker Assays

In general, immunoassays involve contacting a sample containing or suspected of containing a biomarker of interest with at least one antibody that specifically binds to the biomarker. A signal is then generated indicative of the presence or amount of complexes formed by the binding of polypeptides in the sample to the antibody. The signal is then related to the presence or amount of the biomarker in the sample. Numerous methods and devices are well known to the skilled artisan for the detection and analysis of biomarkers. See, e.g., U.S. Pat. Nos. 6,143,576; 6,113,855; 6,019,944; 5,985,579; 5,947,124; 5,939,272; 5,922,615; 5,885,527; 5,851,776; 5,824,799; 5,679,526; 5,525,524; and 5,480,792, and The Immunoassay Handbook, David Wild, ed. Stockton Press, New York, 1994, each of which is hereby incorporated by reference in its entirety, including all tables, figures and claims.

The assay devices and methods known in the art can utilize labeled molecules in various sandwich, competitive, or non-competitive assay formats, to generate a signal that is related to the presence or amount of the biomarker of interest. Suitable assay formats also include chromatographic, mass spectrographic, and protein “blotting” methods. Additionally, certain methods and devices, such as biosensors and optical immunoassays, may be employed to determine the presence or amount of analytes without the need for a labeled molecule. See, e.g., U.S. Pat. Nos. 5,631,171; and 5,955,377, each of which is hereby incorporated by reference in its entirety, including all tables, figures and claims. One skilled in the art also recognizes that robotic instrumentation including but not limited to Beckman ACCESS®, Abbott AXSYM®, Roche ELECSYS®, Dade Behring STRATUS® systems are among the immunoassay analyzers that are capable of performing immunoassays. But any suitable immunoassay may be utilized, for example, enzyme-linked immunoassays (ELISA), radioimmunoassays (RIAs), competitive binding assays, and the like.

Antibodies or other polypeptides may be immobilized onto a variety of solid supports for use in assays. Solid phases that may be used to immobilize specific binding members include those developed and/or used as solid phases in solid phase binding assays. Examples of suitable solid phases include membrane filters, cellulose-based papers, beads (including polymeric, latex and paramagnetic particles), glass, silicon wafers, microparticles, nanoparticles, TENTAGEL™ resins (Rapp Polymere GmbH), AGROGEL™ resins (I.LS.A. Industria Lavorazione Sottoprodotti Animali S.P.A.), polyethylene glycol and acrylamide (PEGA) gels, SPOCC gels, and multiple-well plates. An assay strip could be prepared by coating the antibody or a plurality of antibodies in an array on solid support. This strip could then be dipped into the test sample and then processed quickly through washes and detection steps to generate a measurable signal, such as a colored spot. Antibodies or other polypeptides may be bound to specific zones of assay devices either by conjugating directly to an assay device surface, or by indirect binding. In an example of the latter case, antibodies or other polypeptides may be immobilized on particles or other solid supports, and that solid support immobilized to the device surface.

Biological assays require methods for detection, and one of the most common methods for quantitation of results is to conjugate a detectable label to a protein or nucleic acid that has affinity for one of the components in the biological system being studied. Detectable labels may include molecules that are themselves detectable (e.g., fluorescent moieties, electrochemical labels, metal chelates, etc.) as well as molecules that may be indirectly detected by production of a detectable reaction product (e.g., enzymes such as horseradish peroxidase, alkaline phosphatase, etc.) or by a specific binding molecule which itself may be detectable (e.g., biotin, digoxigenin, maltose, oligohistidine, 2,4-dintrobenzene, phenylarsenate, ssDNA, dsDNA, etc.).

Preparation of solid phases and detectable label conjugates often comprise the use of chemical cross-linkers. Cross-linking reagents contain at least two reactive groups, and are divided generally into homofunctional cross-linkers (containing identical reactive groups) and heterofunctional cross-linkers (containing non-identical reactive groups). Homobifunctional cross-linkers that couple through amines, sulfhydryls or react non-specifically are available from many commercial sources. Maleimides, alkyl and aryl halides, alpha-haloacyls and pyridyl disulfides are thiol reactive groups. Maleimides, alkyl and aryl halides, and alpha-haloacyls react with sulfhydryls to form thiol ether bonds, while pyridyl disulfides react with sulfhydryls to produce mixed disulfides. The pyridyl disulfide product is cleavable. Imidoesters are also very useful for protein-protein cross-links A variety of heterobifunctional cross-linkers, each combining different attributes for successful conjugation, are commercially available.

In certain aspects, the present invention provides kits for the analysis of the described kidney injury markers. The kit comprises reagents for the analysis of at least one test sample which comprise at least one antibody that a kidney injury marker. The kit can also include devices and instructions for performing one or more of the diagnostic and/or prognostic correlations described herein. Preferred kits will comprise an antibody pair for performing a sandwich assay, or a labeled species for performing a competitive assay, for the analyte. Preferably, an antibody pair comprises a first antibody conjugated to a solid phase and a second antibody conjugated to a detectable label, wherein each of the first and second antibodies that bind a kidney injury marker. Most preferably each of the antibodies are monoclonal antibodies. The instructions for use of the kit and performing the correlations can be in the form of labeling, which refers to any written or recorded material that is attached to, or otherwise accompanies a kit at any time during its manufacture, transport, sale or use. For example, the term labeling encompasses advertising leaflets and brochures, packaging materials, instructions, audio or video cassettes, computer discs, as well as writing imprinted directly on kits.

Antibodies

The term “antibody” as used herein refers to a peptide or polypeptide derived from, modeled after or substantially encoded by an immunoglobulin gene or immunoglobulin genes, or fragments thereof, capable of specifically binding an antigen or epitope. See, e.g. Fundamental Immunology, 3rd Edition, W. E. Paul, ed., Raven Press, N.Y. (1993); Wilson (1994; J. Immunol. Methods 175:267-273; Yarmush (1992) J. Biochem. Biophys. Methods 25:85-97. The term antibody includes antigen-binding portions, i.e., “antigen binding sites,” (e.g., fragments, subsequences, complementarity determining regions (CDRs)) that retain capacity to bind antigen, including (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CH1 domains; (ii) a F(ab′)2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CH1 domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb fragment (Ward et al., (1989) Nature 341:544-546), which consists of a VH domain; and (vi) an isolated complementarity determining region (CDR). Single chain antibodies are also included by reference in the term “antibody.”

Antibodies used in the immunoassays described herein preferably specifically bind to a kidney injury marker of the present invention. The term “specifically binds” is not intended to indicate that an antibody binds exclusively to its intended target since, as noted above, an antibody binds to any polypeptide displaying the epitope(s) to which the antibody binds. Rather, an antibody “specifically binds” if its affinity for its intended target is about 5-fold greater when compared to its affinity for a non-target molecule which does not display the appropriate epitope(s). Preferably the affinity of the antibody will be at least about 5 fold, preferably 10 fold, more preferably 25-fold, even more preferably 50-fold, and most preferably 100-fold or more, greater for a target molecule than its affinity for a non-target molecule. In preferred embodiments, Preferred antibodies bind with affinities of at least about 10⁷ M⁻¹, and preferably between about 10⁸ M⁻¹ to about 10⁹ M⁻¹, about 10⁹ M⁻¹ to about 10¹⁰ M⁻¹, or about 10¹⁰ M⁻¹ to about 10¹² M⁻¹.

Affinity is calculated as K_(d)=k_(off)/k_(on) (k_(off) is the dissociation rate constant, K_(on) is the association rate constant and K_(d) is the equilibrium constant). Affinity can be determined at equilibrium by measuring the fraction bound (r) of labeled ligand at various concentrations (c). The data are graphed using the Scatchard equation: r/c=K(n−r): where r=moles of bound ligand/mole of receptor at equilibrium; c=free ligand concentration at equilibrium; K=equilibrium association constant; and n=number of ligand binding sites per receptor molecule. By graphical analysis, r/c is plotted on the Y-axis versus r on the X-axis, thus producing a Scatchard plot. Antibody affinity measurement by Scatchard analysis is well known in the art. See, e.g., van Erp et al., J. Immunoassay 12: 425-43, 1991; Nelson and Griswold, Comput. Methods Programs Biomed. 27: 65-8, 1988.

The term “epitope” refers to an antigenic determinant capable of specific binding to an antibody. Epitopes usually consist of chemically active surface groupings of molecules such as amino acids or sugar side chains and usually have specific three dimensional structural characteristics, as well as specific charge characteristics. Conformational and nonconformational epitopes are distinguished in that the binding to the former but not the latter is lost in the presence of denaturing solvents.

Numerous publications discuss the use of phage display technology to produce and screen libraries of polypeptides for binding to a selected analyte. See, e.g, Cwirla et al., Proc. Natl. Acad. Sci. USA 87, 6378-82, 1990; Devlin et al., Science 249, 404-6, 1990, Scott and Smith, Science 249, 386-88, 1990; and Ladner et al., U.S. Pat. No. 5,571,698. A basic concept of phage display methods is the establishment of a physical association between DNA encoding a polypeptide to be screened and the polypeptide. This physical association is provided by the phage particle, which displays a polypeptide as part of a capsid enclosing the phage genome which encodes the polypeptide. The establishment of a physical association between polypeptides and their genetic material allows simultaneous mass screening of very large numbers of phage bearing different polypeptides. Phage displaying a polypeptide with affinity to a target bind to the target and these phage are enriched by affinity screening to the target. The identity of polypeptides displayed from these phage can be determined from their respective genomes. Using these methods a polypeptide identified as having a binding affinity for a desired target can then be synthesized in bulk by conventional means. See, e.g., U.S. Pat. No. 6,057,098, which is hereby incorporated in its entirety, including all tables, figures, and claims.

The antibodies that are generated by these methods may then be selected by first screening for affinity and specificity with the purified polypeptide of interest and, if required, comparing the results to the affinity and specificity of the antibodies with polypeptides that are desired to be excluded from binding. The screening procedure can involve immobilization of the purified polypeptides in separate wells of microtiter plates. The solution containing a potential antibody or groups of antibodies is then placed into the respective microtiter wells and incubated for about 30 min to 2 h. The microtiter wells are then washed and a labeled secondary antibody (for example, an anti-mouse antibody conjugated to alkaline phosphatase if the raised antibodies are mouse antibodies) is added to the wells and incubated for about 30 min and then washed. Substrate is added to the wells and a color reaction will appear where antibody to the immobilized polypeptide(s) are present.

The antibodies so identified may then be further analyzed for affinity and specificity in the assay design selected. In the development of immunoassays for a target protein, the purified target protein acts as a standard with which to judge the sensitivity and specificity of the immunoassay using the antibodies that have been selected. Because the binding affinity of various antibodies may differ; certain antibody pairs (e.g., in sandwich assays) may interfere with one another sterically, etc., assay performance of an antibody may be a more important measure than absolute affinity and specificity of an antibody.

Assay Correlations

The term “correlating” as used herein in reference to the use of biomarkers refers to comparing the presence or amount of the biomarker(s) in a patient to its presence or amount in persons known to suffer from, or known to be at risk of, a given condition; or in persons known to be free of a given condition. Often, this takes the form of comparing an assay result in the form of a biomarker concentration to a predetermined threshold selected to be indicative of the occurrence or nonoccurrence of a disease or the likelihood of some future outcome.

Selecting a diagnostic threshold involves, among other things, consideration of the probability of disease, distribution of true and false diagnoses at different test thresholds, and estimates of the consequences of treatment (or a failure to treat) based on the diagnosis. For example, when considering administering a specific therapy which is highly efficacious and has a low level of risk, few tests are needed because clinicians can accept substantial diagnostic uncertainty. On the other hand, in situations where treatment options are less effective and more risky, clinicians often need a higher degree of diagnostic certainty. Thus, cost/benefit analysis is involved in selecting a diagnostic threshold.

Suitable thresholds may be determined in a variety of ways. For example, one recommended diagnostic threshold for the diagnosis of acute myocardial infarction using cardiac troponin is the 97.5^(th) percentile of the concentration seen in a normal population. Another method may be to look at serial samples from the same patient, where a prior “baseline” result is used to monitor for temporal changes in a biomarker level.

Population studies may also be used to select a decision threshold. Receiver Operating Characteristic (“ROC”) arose from the field of signal detection theory developed during World War II for the analysis of radar images, and ROC analysis is often used to select a threshold able to best distinguish a “diseased” subpopulation from a “nondiseased” subpopulation. A false positive in this case occurs when the person tests positive, but actually does not have the disease. A false negative, on the other hand, occurs when the person tests negative, suggesting they are healthy, when they actually do have the disease. To draw a ROC curve, the true positive rate (TPR) and false positive rate (FPR) are determined as the decision threshold is varied continuously. Since TPR is equivalent with sensitivity and FPR is equal to 1—specificity, the ROC graph is sometimes called the sensitivity vs (1-specificity) plot. A perfect test will have an area under the ROC curve of 1.0; a random test will have an area of 0.5. A threshold is selected to provide an acceptable level of specificity and sensitivity.

In this context, “diseased” is meant to refer to a population having one characteristic (the presence of a disease or condition or the occurrence of some outcome) and “nondiseased” is meant to refer to a population lacking the characteristic. While a single decision threshold is the simplest application of such a method, multiple decision thresholds may be used. For example, below a first threshold, the absence of disease may be assigned with relatively high confidence, and above a second threshold the presence of disease may also be assigned with relatively high confidence. Between the two thresholds may be considered indeterminate. This is meant to be exemplary in nature only.

In addition to threshold comparisons, other methods for correlating assay results to a patient classification (occurrence or nonoccurrence of disease, likelihood of an outcome, etc.) include decision trees, rule sets, Bayesian methods, and neural network methods. These methods can produce probability values representing the degree to which a subject belongs to one classification out of a plurality of classifications.

Measures of test accuracy may be obtained as described in Fischer et al., Intensive Care Med. 29: 1043-51, 2003, and used to determine the effectiveness of a given biomarker. These measures include sensitivity and specificity, predictive values, likelihood ratios, diagnostic odds ratios, and ROC curve areas. The area under the curve (“AUC”) of a ROC plot is equal to the probability that a classifier will rank a randomly chosen positive instance higher than a randomly chosen negative one. The area under the ROC curve may be thought of as equivalent to the Mann-Whitney U test, which tests for the median difference between scores obtained in the two groups considered if the groups are of continuous data, or to the Wilcoxon test of ranks.

As discussed above, suitable tests may exhibit one or more of the following results on these various measures: a specificity of greater than 0.5, preferably at least 0.6, more preferably at least 0.7, still more preferably at least 0.8, even more preferably at least 0.9 and most preferably at least 0.95, with a corresponding sensitivity greater than 0.2, preferably greater than 0.3, more preferably greater than 0.4, still more preferably at least 0.5, even more preferably 0.6, yet more preferably greater than 0.7, still more preferably greater than 0.8, more preferably greater than 0.9, and most preferably greater than 0.95; a sensitivity of greater than 0.5, preferably at least 0.6, more preferably at least 0.7, still more preferably at least 0.8, even more preferably at least 0.9 and most preferably at least 0.95, with a corresponding specificity greater than 0.2, preferably greater than 0.3, more preferably greater than 0.4, still more preferably at least 0.5, even more preferably 0.6, yet more preferably greater than 0.7, still more preferably greater than 0.8, more preferably greater than 0.9, and most preferably greater than 0.95; at least 75% sensitivity, combined with at least 75% specificity; a ROC curve area of greater than 0.5, preferably at least 0.6, more preferably 0.7, still more preferably at least 0.8, even more preferably at least 0.9, and most preferably at least 0.95; an odds ratio different from 1, preferably at least about 2 or more or about 0.5 or less, more preferably at least about 3 or more or about 0.33 or less, still more preferably at least about 4 or more or about 0.25 or less, even more preferably at least about 5 or more or about 0.2 or less, and most preferably at least about 10 or more or about 0.1 or less; a positive likelihood ratio (calculated as sensitivity/(1-specificity)) of greater than 1, at least 2, more preferably at least 3, still more preferably at least 5, and most preferably at least 10; and or a negative likelihood ratio (calculated as (1-sensitivity)/specificity) of less than 1, less than or equal to 0.5, more preferably less than or equal to 0.3, and most preferably less than or equal to 0.1

Additional clinical indicia may be combined with the kidney injury marker assay result(s) of the present invention. These include other biomarkers related to renal status. Examples include the following, which recite the common biomarker name, followed by the Swiss-Prot entry number for that biomarker or its parent: Actin (P68133); Adenosine deaminase binding protein (DPP4, P27487); Alpha-1-acid glycoprotein 1 (P02763); Alpha-1-microglobulin (P02760); Albumin (P02768); Angiotensinogenase (Renin, P00797); Annexin A2 (P07355); Beta-glucuronidase (P08236); B-2-microglobulin (P61679); Beta-galactosidase (P16278); BMP-7 (P18075); Brain natriuretic peptide (proBNP, BNP-32, NTproBNP; P16860); Calcium-binding protein Beta (S100-beta, P04271); Carbonic anhydrase (Q16790); Casein Kinase 2 (P68400); Cathepsin B (P07858); Ceruloplasmin (P00450); Clusterin (P10909); Complement C3 (P01024); Cysteine-rich protein (CYR61, 000622); Cytochrome C (P99999); Epidermal growth factor (EGF, P01133); Endothelin-1 (P05305); Exosomal Fetuin-A (P02765); Fatty acid-binding protein, heart (FABP3, P05413); Fatty acid-binding protein, liver (P07148); Ferritin (light chain, P02793; heavy chain P02794); Fructose-1,6-biphosphatase (P09467); GRO-alpha (CXCL1, (P09341); Growth Hormone (P01241); Hepatocyte growth factor (P14210); Insulin-like growth factor I (P01343); Immunoglobulin G; Immunoglobulin Light Chains (Kappa and Lambda); Interferon gamma (P01308); Lysozyme (P61626); Interleukin-1alpha (P01583); Interleukin-2 (P60568); Interleukin-4 (P60568); Interleukin-9 (P15248); Interleukin-12p40 (P29460); Interleukin-13 (P35225); Interleukin-16 (Q14005); L1 cell adhesion molecule (P32004); Lactate dehydrogenase (P00338); Leucine Aminopeptidase (P28838); Meprin A-alpha subunit (Q16819); Meprin A-beta subunit (Q16820); Midkine (P21741); MIP2-alpha (CXCL2, P19875); MMP-2 (P08253); MMP-9 (P14780); Netrin-1 (095631); Neutral endopeptidase (P08473); Osteopontin (P10451); Renal papillary antigen 1 (RPA1); Renal papillary antigen 2 (RPA2); Retinol binding protein (P09455); Ribonuclease; S100 calcium-binding protein A6 (P06703); Serum Amyloid P Component (P02743); Sodium/Hydrogen exchanger isoform (NHE3, P48764); Spermidine/spermine N1-acetyltransferase (P21673); TGF-Beta1 (P01137); Transferrin (P02787); Trefoil factor 3 (TFF3, Q07654); Toll-Like protein 4 (000206); Total protein; Tubulointerstitial nephritis antigen (Q9UJW2); Uromodulin (Tamm-Horsfall protein, P07911).

For purposes of risk stratification, Adiponectin (Q15848); Alkaline phosphatase (P05186); Aminopeptidase N (P15144); CalbindinD28k (P05937); Cystatin C (P01034); 8 subunit of FIFO ATPase (P03928); Gamma-glutamyltransferase (P19440); GSTa (alpha-glutathione-S-transferase, P08263); GSTpi (Glutathione-S-transferase P; GST class-pi; P09211); IGFBP-1 (P08833); IGFBP-2 (P18065); IGFBP-6 (P24592); Integral membrane protein 1 (Itm1, P46977); Interleukin-6 (P05231); Interleukin-8 (P10145); Interleukin-18 (Q14116); IP-10 (10 kDa interferon-gamma-induced protein, P02778); IRPR (IFRD1, 000458); Isovaleryl-CoA dehydrogenase (IVD, P26440); I-TAC/CXCL11 (014625); Keratin 19 (P08727); Kim-1 (Hepatitis A virus cellular receptor 1, 043656); L-arginine:glycine amidinotransferase (P50440); Leptin (P41159); Lipocalin2 (NGAL, P80188); MCP-1 (P13500); MIG (Gamma-interferon-induced monokine Q07325); MIP-la (P10147); MIP-3a (P78556); MIP-1beta (P13236); MIP-1d (Q16663); NAG (N-acetyl-beta-D-glucosaminidase, P54802); Organic ion transporter (OCT2, 015244); Osteoprotegerin (014788); P8 protein (060356); Plasminogen activator inhibitor 1 (PAI-1, P05121); ProANP (1-98) (P01160); Protein phosphatase 1-beta (PPI-beta, P62140); Rab GDI-beta (P50395); Renal kallikrein (Q86U61); RT1.B-1 (alpha) chain of the integral membrane protein (Q5Y7A8); Soluble tumor necrosis factor receptor superfamily member 1A (sTNFR-I, P19438); Soluble tumor necrosis factor receptor superfamily member 1B (sTNFR-II, P20333); Tissue inhibitor of metalloproteinases 3 (TIMP-3, P35625); uPAR (Q03405) may be combined with the kidney injury marker assay result(s) of the present invention.

Other clinical indicia which may be combined with the kidney injury marker assay result(s) of the present invention includes demographic information (e.g., weight, sex, age, race), medical history (e.g., family history, type of surgery, pre-existing disease such as aneurism, congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, proteinuria, renal insufficiency, or sepsis, type of toxin exposure such as NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, or streptozotocin), clinical variables (e.g., blood pressure, temperature, respiration rate), risk scores (APACHE score, PREDICT score, TIMI Risk Score for UA/NSTEMI, Framingham Risk Score), a urine total protein measurement, a glomerular filtration rate, an estimated glomerular filtration rate, a urine production rate, a serum or plasma creatinine concentration, a renal papillary antigen 1 (RPA1) measurement; a renal papillary antigen 2 (RPA2) measurement; a urine creatinine concentration, a fractional excretion of sodium, a urine sodium concentration, a urine creatinine to serum or plasma creatinine ratio, a urine specific gravity, a urine osmolality, a urine urea nitrogen to plasma urea nitrogen ratio, a plasma BUN to creatinine ratio, and/or a renal failure index calculated as urine sodium/(urine creatinine/plasma creatinine). Other measures of renal function which may be combined with the kidney injury marker assay result(s) are described hereinafter and in Harrison's Principles of Internal Medicine, 17^(th) Ed., McGraw Hill, New York, pages 1741-1830, and Current Medical Diagnosis & Treatment 2008, 47^(th) Ed, McGraw Hill, New York, pages 785-815, each of which are hereby incorporated by reference in their entirety.

Combining assay results/clinical indicia in this manner can comprise the use of multivariate logistical regression, loglinear modeling, neural network analysis, n-of-m analysis, decision tree analysis, etc. This list is not meant to be limiting.

Diagnosis of Acute Renal Failure

As noted above, the terms “acute renal (or kidney) injury” and “acute renal (or kidney) failure” as used herein are defined in part in terms of changes in serum creatinine from a baseline value. Most definitions of ARF have common elements, including the use of serum creatinine and, often, urine output. Patients may present with renal dysfunction without an available baseline measure of renal function for use in this comparison. In such an event, one may estimate a baseline serum creatinine value by assuming the patient initially had a normal GFR. Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. Glomerular filtration rate (GFR) can be calculated by measuring any chemical that has a steady level in the blood, and is freely filtered but neither reabsorbed nor secreted by the kidneys. GFR is typically expressed in units of ml/min:

${GFR} = \frac{{Urine}\mspace{14mu}{Concentration} \times {Urine}\mspace{14mu}{Flow}}{{Plasma}\mspace{14mu}{Concentration}}$

By normalizing the GFR to the body surface area, a GFR of approximately 75-100 ml/min per 1.73 m² can be assumed. The rate therefore measured is the quantity of the substance in the urine that originated from a calculable volume of blood.

There are several different techniques used to calculate or estimate the glomerular filtration rate (GFR or eGFR). In clinical practice, however, creatinine clearance is used to measure GFR. Creatinine is produced naturally by the body (creatinine is a metabolite of creatine, which is found in muscle). It is freely filtered by the glomerulus, but also actively secreted by the renal tubules in very small amounts such that creatinine clearance overestimates actual GFR by 10-20%. This margin of error is acceptable considering the ease with which creatinine clearance is measured.

Creatinine clearance (CCr) can be calculated if values for creatinine's urine concentration (U_(Cr)), urine flow rate (V), and creatinine's plasma concentration (P_(Cr)) are known. Since the product of urine concentration and urine flow rate yields creatinine's excretion rate, creatinine clearance is also said to be its excretion rate (U_(Cr)×V) divided by its plasma concentration. This is commonly represented mathematically as:

$C_{Cr} = \frac{U_{Cr} \times V}{P_{Cr}}$

Commonly a 24 hour urine collection is undertaken, from empty-bladder one morning to the contents of the bladder the following morning, with a comparative blood test then taken:

$C_{Cr} = \frac{U_{Cr} \times 24\text{-}{hour}\mspace{14mu}{volume}}{P_{Cr} \times 24 \times 60\mspace{14mu}{mins}}$

To allow comparison of results between people of different sizes, the CCr is often corrected for the body surface area (BSA) and expressed compared to the average sized man as ml/min/1.73 m2. While most adults have a BSA that approaches 1.7 (1.6-1.9), extremely obese or slim patients should have their CCr corrected for their actual BSA:

$C_{{Cr} - {corrected}} = \frac{C_{Cr} \times 1.73}{BSA}$

The accuracy of a creatinine clearance measurement (even when collection is complete) is limited because as glomerular filtration rate (GFR) falls creatinine secretion is increased, and thus the rise in serum creatinine is less. Thus, creatinine excretion is much greater than the filtered load, resulting in a potentially large overestimation of the GFR (as much as a twofold difference). However, for clinical purposes it is important to determine whether renal function is stable or getting worse or better. This is often determined by monitoring serum creatinine alone. Like creatinine clearance, the serum creatinine will not be an accurate reflection of GFR in the non-steady-state condition of ARF. Nonetheless, the degree to which serum creatinine changes from baseline will reflect the change in GFR. Serum creatinine is readily and easily measured and it is specific for renal function.

For purposes of determining urine output on a Urine output on a mL/kg/hr basis, hourly urine collection and measurement is adequate. In the case where, for example, only a cumulative 24-h output was available and no patient weights are provided, minor modifications of the RIFLE urine output criteria have been described. For example, Bagshaw et al., Nephrol. Dial. Transplant. 23: 1203-1210, 2008, assumes an average patient weight of 70 kg, and patients are assigned a RIFLE classification based on the following: <35 mL/h (Risk), <21 mL/h (Injury) or <4 mL/h (Failure).

Selecting a Treatment Regimen

Once a diagnosis is obtained, the clinician can readily select a treatment regimen that is compatible with the diagnosis, such as initiating renal replacement therapy, withdrawing delivery of compounds that are known to be damaging to the kidney, kidney transplantation, delaying or avoiding procedures that are known to be damaging to the kidney, modifying diuretic administration, initiating goal directed therapy, etc. The skilled artisan is aware of appropriate treatments for numerous diseases discussed in relation to the methods of diagnosis described herein. See, e.g., Merck Manual of Diagnosis and Therapy, 17th Ed. Merck Research Laboratories, Whitehouse Station, N J, 1999. In addition, since the methods and compositions described herein provide prognostic information, the markers of the present invention may be used to monitor a course of treatment. For example, improved or worsened prognostic state may indicate that a particular treatment is or is not efficacious.

One skilled in the art readily appreciates that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The examples provided herein are representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention.

Example 1: Contrast-Induced Nephropathy Sample Collection

The objective of this sample collection study is to collect samples of plasma and urine and clinical data from patients before and after receiving intravascular contrast media. Approximately 250 adults undergoing radiographic/angiographic procedures involving intravascular administration of iodinated contrast media are enrolled. To be enrolled in the study, each patient must meet all of the following inclusion criteria and none of the following exclusion criteria:

Inclusion Criteria

males and females 18 years of age or older;

undergoing a radiographic/angiographic procedure (such as a CT scan or coronary intervention) involving the intravascular administration of contrast media;

expected to be hospitalized for at least 48 hours after contrast administration.

able and willing to provide written informed consent for study participation and to comply with all study procedures.

Exclusion Criteria

renal transplant recipients;

acutely worsening renal function prior to the contrast procedure;

already receiving dialysis (either acute or chronic) or in imminent need of dialysis at enrollment;

expected to undergo a major surgical procedure (such as involving cardiopulmonary bypass) or an additional imaging procedure with contrast media with significant risk for further renal insult within the 48 hrs following contrast administration;

participation in an interventional clinical study with an experimental therapy within the previous 30 days;

known infection with human immunodeficiency virus (HIV) or a hepatitis virus.

Immediately prior to the first contrast administration (and after any pre-procedure hydration), an EDTA anti-coagulated blood sample (10 mL) and a urine sample (10 mL) are collected from each patient. Blood and urine samples are then collected at 4 (±0.5), 8 (±1), 24 (±2) 48 (±2), and 72 (±2) hrs following the last administration of contrast media during the index contrast procedure. Blood is collected via direct venipuncture or via other available venous access, such as an existing femoral sheath, central venous line, peripheral intravenous line or hep-lock. These study blood samples are processed to plasma at the clinical site, frozen and shipped to Astute Medical, Inc., San Diego, Calif. The study urine samples are frozen and shipped to Astute Medical, Inc.

Serum creatinine is assessed at the site immediately prior to the first contrast administration (after any pre-procedure hydration) and at 4 (±0.5), 8 (±1), 24 (±2) and 48 (±2)), and 72 (±2) hours following the last administration of contrast (ideally at the same time as the study samples are obtained). In addition, each patient's status is evaluated through day 30 with regard to additional serum and urine creatinine measurements, a need for dialysis, hospitalization status, and adverse clinical outcomes (including mortality).

Prior to contrast administration, each patient is assigned a risk based on the following assessment: systolic blood pressure <80 mm Hg=5 points; intra-arterial balloon pump=5 points; congestive heart failure (Class III-IV or history of pulmonary edema)=5 points; age >75 yrs=4 points; hematocrit level <39% for men, <35% for women=3 points; diabetes=3 points; contrast media volume=1 point for each 100 mL; serum creatinine level >1.5 g/dL=4 points OR estimated GFR 40-60 mL/min/1.73 m²=2 points, 20-40 mL/min/1.73 m²=4 points, <20 mL/min/1.73 m²=6 points. The risks assigned are as follows: risk for CIN and dialysis: 5 or less total points=risk of CIN—7.5%, risk of dialysis—0.04%; 6-10 total points=risk of CIN—14%, risk of dialysis—0.12%; 11-16 total points=risk of CIN—26.1%, risk of dialysis—1.09%; >16 total points=risk of CIN—57.3%, risk of dialysis—12.8%.

Example 2: Cardiac Surgery Sample Collection

The objective of this sample collection study is to collect samples of plasma and urine and clinical data from patients before and after undergoing cardiovascular surgery, a procedure known to be potentially damaging to kidney function. Approximately 900 adults undergoing such surgery are enrolled. To be enrolled in the study, each patient must meet all of the following inclusion criteria and none of the following exclusion criteria:

Inclusion Criteria

males and females 18 years of age or older;

undergoing cardiovascular surgery;

Toronto/Ottawa Predictive Risk Index for Renal Replacement risk score of at least 2 (Wijeysundera et al., JAMA 297: 1801-9, 2007); and

able and willing to provide written informed consent for study participation and to comply with all study procedures.

Exclusion Criteria

known pregnancy;

previous renal transplantation;

acutely worsening renal function prior to enrollment (e.g., any category of RIFLE criteria);

already receiving dialysis (either acute or chronic) or in imminent need of dialysis at enrollment;

currently enrolled in another clinical study or expected to be enrolled in another clinical study within 7 days of cardiac surgery that involves drug infusion or a therapeutic intervention for AKI;

known infection with human immunodeficiency virus (HIV) or a hepatitis virus.

Within 3 hours prior to the first incision (and after any pre-procedure hydration), an EDTA anti-coagulated blood sample (10 mL), whole blood (3 mL), and a urine sample (35 mL) are collected from each patient. Blood and urine samples are then collected at 3 (±0.5), 6 (±0.5), 12 (±1), 24 (±2) and 48 (±2) hrs following the procedure and then daily on days 3 through 7 if the subject remains in the hospital. Blood is collected via direct venipuncture or via other available venous access, such as an existing femoral sheath, central venous line, peripheral intravenous line or hep-lock. These study blood samples are frozen and shipped to Astute Medical, Inc., San Diego, Calif. The study urine samples are frozen and shipped to Astute Medical, Inc.

Example 3: Acutely Ill Subject Sample Collection

The objective of this study is to collect samples from acutely ill patients. Approximately 900 adults expected to be in the ICU for at least 48 hours will be enrolled. To be enrolled in the study, each patient must meet all of the following inclusion criteria and none of the following exclusion criteria:

Inclusion Criteria

males and females 18 years of age or older;

Study population 1: approximately 300 patients that have at least one of:

shock (SBP <90 mmHg and/or need for vasopressor support to maintain MAP >60 mmHg and/or documented drop in SBP of at least 40 mmHg); and

sepsis;

Study population 2: approximately 300 patients that have at least one of:

IV antibiotics ordered in computerized physician order entry (CPOE) within 24 hours of enrollment; contrast media exposure within 24 hours of enrollment;

increased Intra-Abdominal Pressure with acute decompensated heart failure; and

severe trauma as the primary reason for ICU admission and likely to be hospitalized in the ICU for 48 hours after enrollment;

Study population 3: approximately 300 patients

expected to be hospitalized through acute care setting (ICU or ED) with a known risk factor for acute renal injury (e.g. sepsis, hypotension/shock (Shock=systolic BP<90 mmHg and/or the need for vasopressor support to maintain a MAP >60 mmHg and/or a documented drop in SBP >40 mmHg), major trauma, hemorrhage, or major surgery); and/or expected to be hospitalized to the ICU for at least 24 hours after enrollment. Exclusion Criteria known pregnancy; institutionalized individuals; previous renal transplantation; known acutely worsening renal function prior to enrollment (e.g., any category of RIFLE criteria); received dialysis (either acute or chronic) within 5 days prior to enrollment or in imminent need of dialysis at the time of enrollment; known infection with human immunodeficiency virus (HIV) or a hepatitis virus; meets only the SBP <90 mmHg inclusion criterion set forth above, and does not have shock in the attending physician's or principal investigator's opinion.

After providing informed consent, an EDTA anti-coagulated blood sample (10 mL) and a urine sample (25-30 mL) are collected from each patient. Blood and urine samples are then collected at 4 (±0.5) and 8 (±1) hours after contrast administration (if applicable); at 12 (±1), 24 (±2), and 48 (±2) hours after enrollment, and thereafter daily up to day 7 to day 14 while the subject is hospitalized. Blood is collected via direct venipuncture or via other available venous access, such as an existing femoral sheath, central venous line, peripheral intravenous line or hep-lock. These study blood samples are processed to plasma at the clinical site, frozen and shipped to Astute Medical, Inc., San Diego, Calif. The study urine samples are frozen and shipped to Astute Medical, Inc.

Example 4. Immunoassay Format

Analytes are is measured using standard sandwich enzyme immunoassay techniques. A first antibody which binds the analyte is immobilized in wells of a 96 well polystyrene microplate. Analyte standards and test samples are pipetted into the appropriate wells and any analyte present is bound by the immobilized antibody. After washing away any unbound substances, a horseradish peroxidase-conjugated second antibody which binds the analyte is added to the wells, thereby forming sandwich complexes with the analyte (if present) and the first antibody. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution comprising tetramethylbenzidine and hydrogen peroxide is added to the wells. Color develops in proportion to the amount of analyte present in the sample. The color development is stopped and the intensity of the color is measured at 540 nm or 570 nm. An analyte concentration is assigned to the test sample by comparison to a standard curve determined from the analyte standards.

Concentrations are expressed in the following examples as follows: Cytoplasmic aspartate aminotransferase—μg/mL, soluble Tumor necrosis factor receptor superfamily member 5 (“CD40”)—ng/mL, soluble CD40 Ligand—ng/mL, soluble C-X-C Motif chemokine 16—ng/mL, S100-A12 (“EN-RAGE”)—ng/mL, Eotaxin—pg/mL, soluble E-selectin—ng/mL, Fibronectin—ng/mL, Granulocyte colony-stimulating factor—pg/mL, Granulocyte-macrophage colony-stimulating factor—pg/mL, Heparin-binding growth factor 2—pg/mL, soluble Hepatocyte growth factor receptor—pg/mL, Interleukin-1 receptor antagonist—pg/mL, Interleukin-1 beta—pg/mL, Interleukin-10—pg/mL, Interleukin-15—ng/mL, Interleukin-3—ng/mL, Myeloperoxidase—ng/mL, Nidogen-1—pg/mL, soluble Oxidized low-density lipoprotein receptor 1—ng/mL, Pappalysin-1—mIU/mL, soluble P-selectin glycoprotein ligand 1—U/mL, Antileukoproteinase (“Secretory leukocyte peptidase inhibitor”)—pg/mL, soluble Kit ligand (“Stem cell factor”)—pg/mL, Tissue inhibitor of metalloproteinase 1—ng/mL, Tissue inhibitor of metalloproteinase 2—pg/mL, soluble Tumor necrosis factor—pg/mL, soluble Vascular cell adhesion molecule 1—ng/mL, and Vascular endothelial growth factor A—pg/mL.

Example 5. Apparently Healthy Donor and Chronic Disease Patient Samples

Human urine samples from donors with no known chronic or acute disease (“Apparently Healthy Donors”) were purchased from two vendors (Golden West Biologicals, Inc., 27625 Commerce Center Dr., Temecula, Calif. 92590 and Virginia Medical Research, Inc., 915 First Colonial Rd., Virginia Beach, Va. 23454). The urine samples were shipped and stored frozen at less than −20° C. The vendors supplied demographic information for the individual donors including gender, race (Black/White), smoking status and age.

Human urine samples from donors with various chronic diseases (“Chronic Disease Patients”) including congestive heart failure, coronary artery disease, chronic kidney disease, chronic obstructive pulmonary disease, diabetes mellitus and hypertension were purchased from Virginia Medical Research, Inc., 915 First Colonial Rd., Virginia Beach, Va. 23454. The urine samples were shipped and stored frozen at less than −20 degrees centigrade. The vendor provided a case report form for each individual donor with age, gender, race (Black/White), smoking status and alcohol use, height, weight, chronic disease(s) diagnosis, current medications and previous surgeries.

Example 6. Kidney Injury Markers for Evaluating Renal Status in Patients at RIFLE Stage

Patients from the intensive care unit (ICU) were classified by kidney status as non-injury (0), risk of injury (R), injury (I), and failure (F) according to the maximum stage reached within 7 days of enrollment as determined by the RIFLE criteria.

Two cohorts were defined as (Cohort 1) patients that did not progress beyond stage 0, and (Cohort 2) patients that reached stage R, I, or F within 10 days. To address normal marker fluctuations that occur within patients at the ICU and thereby assess utility for monitoring AKI status, marker levels were measured in urine samples collected for Cohort 1. Marker concentrations were measured in urine samples collected from a subject at 0, 24 hours, and 48 hours prior to reaching stage R, I or F in Cohort 2. In the following tables, the time “prior max stage” represents the time at which a sample is collected, relative to the time a particular patient reaches the lowest disease stage as defined for that cohort, binned into three groups which are +/−12 hours. For example, 24 hr prior for this example (0 vs R, I, F) would mean 24 hr (+/−12 hours) prior to reaching stage R (or I if no sample at R, or F if no sample at R or I).

Each marker was measured by standard immunoassay methods using commercially available assay reagents. A receiver operating characteristic (ROC) curve was generated for each marker and the area under each ROC curve (AUC) was determined. Patients in Cohort 2 were also separated according to the reason for adjudication to stage R, I, or F as being based on serum creatinine measurements (sCr), being based on urine output (UO), or being based on either serum creatinine measurements or urine output. That is, for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements alone, the stage 0 cohort may have included patients adjudicated to stage R, I, or F on the basis of urine output; for those patients adjudicated to stage R, I, or F on the basis of urine output alone, the stage 0 cohort may have included patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements; and for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements or urine output, the stage 0 cohort contains only patients in stage 0 for both serum creatinine measurements and urine output. Also, for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements or urine output, the adjudication method which yielded the most severe RIFLE stage was used.

The ability to distinguish cohort 1 (subjects remaining in RIFLE 0) from Cohort 2 (subjects progressing to RIFLE R, I or F) was determined using ROC analysis. SE is the standard error of the AUC, n is the number of sample or individual patients (“pts,” as indicated). Standard errors were calculated as described in Hanley, J. A., and McNeil, B. J., The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology (1982) 143: 29-36; p values were calculated with a two-tailed Z-test. An AUC <0.5 is indicative of a negative going marker for the comparison, and an AUC >0.5 is indicative of a positive going marker for the comparison.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 1 .

Example 7. Kidney Injury Markers for Evaluating Renal Status in Patients at RIFLE Stages 0 and R

Patients were classified and analyzed as described in Example 6. However, patients that reached stage R but did not progress to stage I or F were grouped with patients from non-injury stage 0 in Cohort 1. Cohort 2 in this example included only patients that progressed to stage I or F. Marker concentrations in urine samples were included for Cohort 1. Marker concentrations in urine samples collected within 0, 24, and 48 hours of reaching stage I or F were included for Cohort 2.

The ability to distinguish cohort 1 (subjects remaining in RIFLE 0 or R) from Cohort 2 (subjects progressing to RIFLE I or F) was determined using ROC analysis.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 2 .

Example 8. Kidney Injury Markers for Evaluating Renal Status in Patients Progressing from Stage R to Stages I and F

Patients were classified and analyzed as described in Example 6, but only those patients that reached Stage R were included in this example. Cohort 1 contained patients that reached stage R but did not progress to stage I or F within 10 days, and Cohort 2 included only patients that progressed to stage I or F. Marker concentrations in urine samples collected within 12 hours of reaching stage R were included in the analysis for both Cohort 1 and 2.

The ability to distinguish cohort 1 (subjects remaining in RIFLE R) from Cohort 2 (subjects progressing to RIFLE I or F) was determined using ROC analysis.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 3 .

Example 9. Kidney Injury Markers for Evaluating Renal Status in Patients at RIFLE Stage 0

Patients were classified and analyzed as described in Example 6. However, patients that reached stage R or I but did not progress to stage F were eliminated from the analysis. Patients from non-injury stage 0 are included in Cohort 1. Cohort 2 in this example included only patients that progressed to stage F. The maximum marker concentrations in urine samples were included for each patient in Cohort 1. The maximum marker concentrations in urine samples collected within 0, 24, and 48 hours of reaching stage F were included for each patient in Cohort 2.

The ability to distinguish cohort 1 (subjects remaining in RIFLE 0 or R) from Cohort 2 (subjects progressing to RIFLE I or F) was determined using ROC analysis.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 4 .

Example 10. Kidney Injury Markers for Evaluating Renal Status in Patients at RIFLE Stage 0

Patients from the intensive care unit (ICU) were classified by kidney status as non-injury (0), risk of injury (R), injury (I), and failure (F) according to the maximum stage reached within 7 days of enrollment as determined by the RIFLE criteria.

Two cohorts were defined as (Cohort 1) patients that did not progress beyond stage 0, and (Cohort 2) patients that reached stage R, I, or F within 10 days. To address normal marker fluctuations that occur within patients at the ICU and thereby assess utility for monitoring AKI status, marker levels were measured in the plasma component of blood samples collected for Cohort 1. Marker concentrations were measured in the plasma component of blood samples collected from a subject at 0, 24 hours, and 48 hours prior to reaching stage R, I or F in Cohort 2. In the following tables, the time “prior max stage” represents the time at which a sample is collected, relative to the time a particular patient reaches the lowest disease stage as defined for that cohort, binned into three groups which are +/−12 hours. For example, 24 hr prior for this example (0 vs R, I, F) would mean 24 hr (+/−12 hours) prior to reaching stage R (or I if no sample at R, or F if no sample at R or I).

Each marker was measured by standard immunoassay methods using commercially available assay reagents. A receiver operating characteristic (ROC) curve was generated for each marker and the area under each ROC curve (AUC) was determined. Patients in Cohort 2 were also separated according to the reason for adjudication to stage R, I, or F as being based on serum creatinine measurements (sCr), being based on urine output (UO), or being based on either serum creatinine measurements or urine output. That is, for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements alone, the stage 0 cohort may have included patients adjudicated to stage R, I, or F on the basis of urine output; for those patients adjudicated to stage R, I, or F on the basis of urine output alone, the stage 0 cohort may have included patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements; and for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements or urine output, the stage 0 cohort contains only patients in stage 0 for both serum creatinine measurements and urine output. Also, for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements or urine output, the adjudication method which yielded the most severe RIFLE stage was used.

The ability to distinguish cohort 1 (subjects remaining in RIFLE 0) from Cohort 2 (subjects progressing to RIFLE R, I or F) was determined using ROC analysis. SE is the standard error of the AUC, n is the number of sample or individual patients (“pts,” as indicated). Standard errors were calculated as described in Hanley, J. A., and McNeil, B. J., The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology (1982) 143: 29-36; p values were calculated with a two-tailed Z-test. An AUC <0.5 is indicative of a negative going marker for the comparison, and an AUC >0.5 is indicative of a positive going marker for the comparison.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 5 .

Example 11. Kidney Injury Markers for Evaluating Renal Status in Patients at RIFLE Stages 0 and R

Patients were classified and analyzed as described in Example 10. However, patients that reached stage R but did not progress to stage I or F were grouped with patients from non-injury stage 0 in Cohort 1. Cohort 2 in this example included only patients that progressed to stage I or F. Marker concentrations in the plasma component of blood samples were included for Cohort 1. Marker concentrations in the plasma component of blood samples collected within 0, 24, and 48 hours of reaching stage I or F were included for Cohort 2.

The ability to distinguish cohort 1 (subjects remaining in RIFLE 0 or R) from Cohort 2 (subjects progressing to RIFLE I or F) was determined using ROC analysis.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 6 .

Example 12. Kidney Injury Markers for Evaluating Renal Status in Patients Progressing from Stage R to Stages I and F

Patients were classified and analyzed as described in Example 10, but only those patients that reached Stage R were included in this example. Cohort 1 contained patients that reached stage R but did not progress to stage I or F within 10 days, and Cohort 2 included only patients that progressed to stage I or F. Marker concentrations in the plasma component of blood samples collected within 12 hours of reaching stage R were included in the analysis for both Cohort 1 and 2.

The ability to distinguish cohort 1 (subjects remaining in RIFLE R) from Cohort 2 (subjects progressing to RIFLE I or F) was determined using ROC analysis.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 7 .

Example 13. Kidney Injury Markers for Evaluating Renal Status in Patients at RIFLE Stage 0

Patients were classified and analyzed as described in Example 10. However, patients that reached stage R or I but did not progress to stage F were eliminated from the analysis. Patients from non-injury stage 0 are included in Cohort 1. Cohort 2 in this example included only patients that progressed to stage F. The maximum marker concentrations in the plasma component of blood samples were included from each patient in Cohort 1. The maximum marker concentrations in the plasma component of blood samples collected within 0, 24, and 48 hours of reaching stage F were included from each patient in Cohort 2.

The ability to distinguish cohort 1 (subjects remaining in RIFLE 0 or R) from Cohort 2 (subjects progressing to RIFLE I or F) was determined using ROC analysis.

Various threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio.

The results of these three analyses for various markers of the present invention are presented in FIG. 8 .

While the invention has been described and exemplified in sufficient detail for those skilled in this art to make and use it, various alternatives, modifications, and improvements should be apparent without departing from the spirit and scope of the invention. The examples provided herein are representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Modifications therein and other uses will occur to those skilled in the art. These modifications are encompassed within the spirit of the invention and are defined by the scope of the claims.

It will be readily apparent to a person skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention.

All patents and publications mentioned in the specification are indicative of the levels of those of ordinary skill in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference.

The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein. Thus, for example, in each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

Other embodiments are set forth within the following claims. 

We claim:
 1. A method for evaluating renal status in a subject and treating the subject based on the evaluation, the method comprising: performing an assay configured to detect Metalloproteinase inhibitor 2 in a body fluid sample obtained from the subject to generate an assay result; correlating the assay result to an increased risk of having acute kidney injury within 7 days of the time at which the sample is obtained from the subject when the assay result is above a predetermined threshold; and treating the subject having the increased risk of having acute kidney injury within 7 days with a compatible treatment regimen, wherein the compatible treatment regimen comprises one or more of initiating renal replacement therapy, withdrawing delivery of compounds that are known to be damaging to the kidney, delaying procedures that are known to be damaging to the kidney, modifying diuretic administration, and monitoring kidney reperfusion.
 2. The method of claim 1, wherein the increased risk of having acute kidney injury within 7 days is an increased risk of having RIFLE stage I or F or AKIN stage II or III acute kidney injury within 7 days.
 3. The method of claim 1, wherein the increased risk of having acute kidney injury within 7 days is an increased risk of having RIFLE stage F or AKIN stage III acute kidney injury within 7 days.
 4. The method of claim 1, wherein said assay result is a measured concentration of Metalloproteinase inhibitor
 2. 5. The method of claim 1, wherein said correlating step comprises correlating the assay result to an increased risk of the subject having acute kidney injury within 48 hours of the time at which the sample is obtained.
 6. The method of claim 1, wherein said correlating step comprises correlating the assay result to an increased risk of the subject having acute kidney injury within 24 hours of the time at which the sample is obtained.
 7. The method of claim 1, wherein said correlating step comprises correlating the assay result to an increased risk of the subject having acute kidney injury within 12 hours of the time at which the sample is obtained.
 8. The method according to claim 1, wherein the subject is in RIFLE stage 0 or R or AKIN stage I at the time at which the sample is obtained.
 9. The method of claim 1, wherein the subject does not have acute kidney injury.
 10. The method of claim 1, wherein the body fluid sample comprises a urine sample, whole blood sample, serum sample, or plasma sample.
 11. The method of claim 1, wherein the increased risk of having acute kidney injury within 7 days is an increased risk of having future acute kidney injury.
 12. The method of claim 1, wherein the correlating step comprises determining that the subject currently has acute kidney injury.
 13. A method of detecting a marker of acute kidney injury in a subject under clinical evaluation for kidney injury, the method comprising performing an assay to detect a level of Metalloproteinase inhibitor 2 within a urine, whole blood, plasma, or serum sample, wherein the sample is obtained from the subject within 7 days after an acute medical event which predisposes the subject for developing acute kidney injury.
 14. The method of claim 13, wherein the sample is obtained within 72 hours after the acute medical event.
 15. The method of claim 13, wherein the acute medical event comprises shock, sepsis, hemorrhage, an ischemic surgery, myocardial infarction, cardiac tamponade, increased intra-abdominal pressure with acute decompensated heart failure, ischemia, pulmonary embolism, pancreatitis, a burn, excessive diuresis, major trauma, or anaphylaxis.
 16. The method of claim 13, wherein the acute medical event comprises exposure to an NSAID, a cyclosporine, tacrolimus, an aminoglycoside, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, a heavy metal, methotrexate, radiopaque contrast media, streptozotocin, an anti-hypertensive drug, an ACE-inhibitor, an angiotensin II receptor blocker, an anesthetic, a β-lactam, a sulfonamide, ciprofloxacin, a thiazide diuretic, furosemide, phenytoin, allopurinol, triamterene, acyclovir, or indinavir.
 17. The method of claim 13, further comprising measuring a volume of urine output, urine flow rate, serum creatinine, or urine creatinine when the sample is obtained or within 7 days after the sample is obtained.
 18. The method of claim 13, wherein the subject has an existing diagnosis of one or more of congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, aneurism, chronic obstructive pulmonary disease, pulmonary hypertension, hypotension, shock, sepsis, liver failure, hypercalcemia, lymphoma, sarcoidosis, leukemia, a ureteral obstruction, and a bladder obstruction, or wherein the subject is on positive-pressure mechanical ventilation.
 19. A method of treating a subject for acute kidney injury, the method comprising: selecting the subject for treatment based on the subject's having a Metalloproteinase inhibitor 2 level in a body fluid sample being above a predetermined threshold indicating an increased risk of having acute kidney injury within 7 days from the time the sample was obtained; and treating the subject with a compatible treatment regimen, wherein the compatible treatment regimen comprises one or more of initiating renal replacement therapy, withdrawing delivery of compounds that are known to be damaging to the kidney, delaying procedures that are known to be damaging to the kidney, modifying diuretic administration, and monitoring kidney reperfusion. 